Data Integration Musings, Circa 1991

I recently stumbled over this very old text. It is really just notes and musings, but thought it was interesting to see some of my earliest thoughts on the data integration problem. Presented as is.

Mechanical Symbol Systems

To what extent can knowledge be thought of as sentences in an internal language of thought?
Should knowledge by seen as an essentially biological, or essentially social, phenomenon?
Can a machine be said to have intentional states, or are all meanings of internal machine representations essentially rooted in human interpretations of them?

Robot Communities

How can robots and humans share knowledge?
Can artificial reasoners act as vehicles for knowledge transfer between humans? (yes, they already are – see work on training systems)

Human Symbol Systems
Structures: Concepts, Facts and Process
Human Culture
Communication Among Individuals

Discourse

The level of discourse among humans is very complex. Researchers in the natural language processing field would tell you that human discourse is very hard to capture in computer systems. Humans of course have no problem following the subject changes and shifting contexts of discourse.
Language is the means through which humans pass information to one another. Historically, verbal communication has been the primary means of conveying information. Through verbal communication, parents teach their children, conveying not just facts, but also concepts and world view. Through socialization, children learn the locally acceptable way in which to exist in the world. Through continual human contact, all persons reinforce their understanding of the world. Culture is a locally defined set of concepts, facts and processes.

Myth

One of the most important transmission devices for human communication is myth. Myth is story-telling, and therefore is largely verbal in nature.

Ritual

Ritual also is used to communicate knowledge and reiterate beliefs among individuals. Ritual is performance, and can be used to teach process.

Information Systems Structures: Concepts, Facts and Process

The conceptual level of a standard information system may be stored in a database’s data dictionary. In some cases, the data dictionary is fairly simplistic, and may actually be hidden within the processes which maintain the database, inaccessible to outside review except by skilled programmers. More sophisticated data dictionaries, such as IBM’s Repository, and other CASE tools, make explicit the machine-level representation of the data contained in the system. The concepts stored in such devices are largely elementary, and idiosynchratic.
They are elementary in that a single concept in a data dictionary will generally refer to a small item of data called variously a “column” or a “field”. What is expressed by a single entry in a data dictionary is a mapping from an application-specific concept, for instance “PART_NUMBER”, to a machine-dependent, computable format (numeric, 12 decimal digits).
A “fact” in a database sense is a single instance or example of a data dictionary concept coupled with a single value.

Communication Across Information Systems, Custom Approaches

Information systems typically have no provision either to generate or understand discursive communication. Typically, information shared between two information systems must be rigidly defined long before transmission begins. This takes human intervention to define transmission carriers, as well as format, and periodicity.

Networks

The ISO OSI seven layers of communication was an initial attempt at defining the medium of computer communication. All computers which required communications services faced the same problems. Much of the work in networking today is geared toward building this ability to communicate. For humans, communication is through the various senses, taking advantage of the natural characteristics of the environment and the physical body. The majority of computers do not share the same senses.
Distributed systems are those in which all individual systems are connected via a network of transmission lines, and in which some level of pre-defined communication has been developed. The development of distributed database systems represents the first steps toward homogenation of mechanical symbol systems.

Electronic Data Interchange

EDI takes the communication process a step farther by introducing a rudimentary level of discourse among individual enterprises. Typically discourse is restricted to payments and orders of material, and typically these interchanges are just as static as earlier developments. The difference here is that human intervention is slowly developing a cultural definition of the information format and content that may be allowed to be transferred.
As standards are developed describing the exact nature and structure of the information that any company may submit or recieve, more of a culture of discourse can be recognized in the process overall. The discourse is of course carried out by humans at this point, as they define a syntax and semantics for the proper transmission of information in the domain of supply, payment, and delivery (commerce).
Although it is ridiculous to talk of an “EDI culture” as a machine-based, self-defining, self-reinforcing collection of symbols in its own right, it is a step in that direction. What EDI, and especially the development of standards for EDI transmissions, represents is an initial attempt to define societal-like communication among computers. In effect, EDI is extending the means of human discourse into the realm of high-speed transaction processing. The standards being developed for the format and type of transactions allowed represent a formalization and agreement among the society of business enterprises on the future language of commerce.

Raising Consciousness in Mechanical Symbol Systems

In order to partake of the richness and flexibility of human symbol systems, machines must be given control of their own senses. They must become aware of their environment. They must become aware of their own “bodies”. This is the mind-body problem.
mission lines, and in which some level of pre-defined communication has been developed. The development of distributed database systems represents the first steps toward homogenation of mechanical symbol systems.

Electronic Data Interchange

EDI takes the communication process a step farther by introducing a rudimentary level… (Author note: transcript cuts off right here)

You Can’t Store Meaning In Software

I’ve had some recent conversations at work which made me realize I needed to make some of the implications of my other posts more obvious and explicit. In this case, while I posted awhile ago about How Meaning Attaches to Data Structures I never really carried the conversation forward.

Here is the basic, fundamental mistake that we software developers make (and others) in talking about our own software. Namely, we start thinking that the data structure and programs actually and directly hold the meaning we intend. That if we do things right, that our data structures, be they tables with rows and columns or POJOs (Plain Old Java Objects) in a Domain layer, just naturally and explicitly contain the meaning.

The problem is, that whatever symbols we make in the computer, the computer can only hold structure. Our programs are only manipulating addresses in memory (or disk) and only comparing sequences of bits (themselves just voltages on wires). Now through the programming process, we developers create extremely sophisticated manipulations of these bits, and we are constantly translating one sequence of bits into another in some regular, predictable way. This includes pushing our in-memory patterns onto storage media (and typically constructing a different pattern of bits), and pushing our in-memory patterns onto video screens in forms directly interpretable by trained human users (such as displaying ASCII numbers as characters in an alphabet forming words in a language which can be read).

This is all very powerful, and useful, but it works only because we humans have projected meaning onto the bit patterns and processes. We have written the code so that our bit symbol representing a “1” can be added to another bit symbol “1” and the program will produce a new bit symbol that we, by convention, will say represents a value of “2”.

The software doesn’t know what any of this means. We could have just as easily defined the meaning of the same signs and processing logic in some other way (perhaps, for instance, to indicate that we have received signals from two different origins, maybe to trigger other processing).

Why This Is Important

The comment was made to me that “if we can just get the conceptual model right, then the programming should be correct.”  I won’t go into the conversation more deeply, but it lead me to thinking how to explain why that was not the best idea.

Here is my first attempt.

No matter how good a conceptual model you create, how complete, how general, how accurate to a domain, there is no way to put it into the computer. The only convention we have as programmers when we want to project meaning into software is that we define physical signs and processes which manipulate them in a way consistent with the meaning we intend.

This is true whether we manifest our conceptual model in a data model, or an object model, or a Semantic Web ontology, or a rules framework, or a set of tabs on an Excel file, or an XML schema, or … The point is the computer can only store the sign portion of our symbols and never the concept so if you intend to create a conceptual model of a domain, and have it inform and/or direct the operation of your software, you are basically just writing more signs and processes.

Now if you want some flexibility, there are many frameworks you can use to create a symbollic “model” of a “conceptual model” and then you can tie your actual solution to this other layer of software. But in the most basic, reductionist sense, all you’ve done is write more software manipulating one set of signs in a manner that permits them to be interpreted as representing a second set of signs, which themselves only have meaning in the human interpretation.

Meaning Over Transformation

This entry is probably ahead of the story, but I wanted to start moving into this subject and I’m not yet organized. It should make more sense later on when I’ve explained such things as the “magical” function M() more thoroughly.

Review: The Magical Function “M()”

As a review for those who may not have seen this function previously on this site, I have invented a mysterious and powerful function over all things used as signs by humans. Named the “M()” function, I can apply it to any symbol or set of symbols of any type and it will return what that symbol represents. I call it the “M() function because it takes something which is a symbol and it returns its meaning (that’s all of its meaning).

How Meaning Carries Over Symbol Transformations

When we move information from one data structure to another, we may or may not use a reversible process. By this I mean that sometimes a transformation is a one-way operation because some of the meaning is lost in the transformation. Sometimes this loss is trivial, but sometimes it is crucial. (Alternatively, there can be transformations which actually add meaning through deductive reasoning and projection. SFAT (story for another time))

Whether a transformation loses information or not, there are some interesting conclusions we can illustrate using my magical, mysterious function M(). Imagine a set β of data structure instances (data) in an anchor state. The full meaning of that data can be expressed as M(β). Now imagine a transformation operation T which maps all of the data in β onto a second set of data Δ.

T : β |–> Δ such that for each symbol σ in β, there is a corresponding symbol δ in Δ that represents the same things, and σ <> δ

By definition, since we have defined T to be an identity function over the meaning of β, then we can conclude that if we apply M() before and after the transformation, we will find ourselves with an equivalence of meaning, as follows:

By definition: T(β) = Δ

Hence: M( T(β) ) ≡ M( Δ )

Also, by definition of T(), then M( β )  ≡ M( T(β) )

Finally, we conclude: M( β ) ≡ M( Δ )

Now, obviously this is a trivial example concocted to show the basic idea of M(). Through the manner by which we have defined our scenario, we get an obvious conclusion. There are many instances where our transformation functions will not produce equivalent sets of symbols. When T() does produce an equivalence, we call it a “loss-less” transformation (borrowing a term from information theory) because no information is lost through its operation.

Another relationship we claim can also be defined in this manner is namely that of semantic equivalence.  This should be obvious as well, from reflection, as I was careful above to refer to “equivalence of meaning”, which is really what I mean when I say two things are semantically equivalent. In this situation, we defined T() as an operation over symbols such that one set of symbols were replaced with a different set of symbols, and the individual pairs of symbols were NOT THE SAME (σ <> δ)! In a most practical sense, what is happening is that we are exchanging one kind of data structure (or sign) with another, such that the two symbols are not syntactically equivalent (they have different signs)  but they remain semantically equivalent. (You can see some of my thoughts on semantic and syntactic equivalence by searching entries tagged and/or categorized “equivalence” and “comparability“.)

A quick example might be a data structure holding a person’s name. Let’s say that within β the name is stored as a string of characters in signature order (first name  middle name  last name) such as “John Everett Doe”. This symbol refers to a person by that name, and so if we apply M() to it, we would recognize the meaning of the symbol to be the thought of that person in our head. Now by applying T() to this symbol, we convert it to a symbol in Δ, also constructed from a string data structure, but this time the name components are listed in phone directory order (last name, first name middle name) such as “Doe, John Everett”. Clearly, while the syntactic presentation of the transformed symbol is completely different, the meaning is exactly the same.

T(“John Everett Doe”) = “Doe, John Everett”

M( T(“John Everett Doe”) ) ≡ M( “Doe, John Everett” )

M( “John Everett Doe” ) ≡ M( T(“John Everett Doe”) )

M( “John Everett Doe” ) ≡ M( “Doe, John Everett” )

“John Everett Doe” <> “Doe, John Everett”

When the transformation is loss less, there is a good chance that it is also reversible, that an inverse transformation T ‘ () can be created. As an inverse transformation, we would expect that T ‘ () will convert symbols in Δ back into symbols in β, and that it will also carry the meaning with complete fidelity back onto the symbols of β. Hence, given this expectation, we can make the following statements about T ‘ ():

T ‘ (Δ) = β

M( T ‘ (Δ) ) ≡ M( β )

By definition of T ‘ (), then M( Δ )  ≡ M( T ‘ (Δ) )

And again: M( Δ ) ≡ M( β )

Extending our example a moment, if we apply T ‘ () to our symbol, “Doe, John Everett”, we will get our original symbol “John Everett Doe”.

Meaning Over “Lossy” Transformation

So what happens when our transformation is not loss-less over meaning? Let’s imagine another transformation which transforms all of the symbols σ in β into symbols ε in Ε. Again, we’ll say that σ <> ε, but we’ll also define T ‘ ‘ () as “lossy over meaning” – which just indicates that as the symbols are transformed, some of the meaning of the original symbol is lost in translation. In our evolving notation, this would be stated as follows:

T ‘ ‘ (β) = Ε

M( T ‘ ‘ (β) ) ≡ M( Ε )

However, by the definition of T ‘ ‘ (), then M( β )  !≡ M( T ‘ ‘ (β) )

Therefore: M( β ) !≡ M( Ε )

In this case, while every symbol in β generates a symbol in Ε, the total information content of Ε is less than that in B. Hence, the symbols of the two sets are no longer semantically equivalent. With transformations such as this, the likelihood that there is an inverse transformation that could restore β from Ε becomes more unlikely. Logically, it would seem there could be no circumstances where β could be reconstituted from Ε alone, since otherwise the information would have been carried completely across the transformation. I don’t outright make this conclusion, however, since it depends on the nature of the information lost.

An example of a reversible, lossy transformation would include the substitution of a primary key value for an entire row of other data which in itself does not carry all of the information for which it is a key, but which can be used in an index fashion to recall the full set of data. For example, if we created a key value symbol consisting of a person’s social security number and last name, we could use that as a reference for that person. This reference symbol could be passed as a marker to another context (from β to Ε, say) where it could be interpreted only partially as a reference to a person. But which person and what other attributes are known about that person in the new context Ε if we define the transformation in such a way that all of the symbols for these other attributes stay in β? Not much, making this transformation one where information is “lost” in Ε.  However, due to its construction from β, the key symbol could still be used on the inverse transformation back to β to reconstitute the missing information (presuming β retains it).

An example of a one-way transformation might be one that drops the middle name and last name components from a string containing a name. Hence, T ‘ ‘ ( “John Everett Doe” ) might be defined to result in a new symbol, “John”. Since many other symbols could map to the same target, creating an inverse transformation without using other information becomes impossible.

Example of How Meaning Is Attached to Structure

What follows is a detailed example of the thought process followed by a software developer to create a class of data structures and how meaning is attached to those structures.

Consider that the meaning of one data structure may be composed of the collection of meanings of a set of smaller structures which themselves have meaning. Take the following description as the meaning to be represented by a structure:

An employee is a human being or person. Each employee has a unique identity of their own. Each employee has a name, which may be the same as the name of a different person or employee. Being human, each employee has an age, calculated by counting the number of years since they were born up to some other point in time (such as present day).Each person of a certain age may enter into a marriage with another human being, who in turn also has their own identity and other attributes of a person.

To represent this information using data structures (i.e., to project the meaning of this information onto a data structure), we might tie the various concepts about a human being/employee to a computer-based data structure. Recognizing that a human being is an object with many additional characteristics of which we might want to know about, we might choose to project the concept of “human beings” or “people” onto a relational table and the concept of a particular individual onto one of that table’s rows (or a similar record structure).

This table would represent a set of individual human beings, and onto each row of the table would be projected the meaning of a particular human being. Saying this again in a more conventional manner, we would say that each row of the table will reference a singular and particular human being, the all of the rows will represent the set of all human beings we’ve observed in the context of our usage of the computer system.

In a more mathematical vein, we would define a projection Þ from the set of actual human beings Α onto Š, (Þ(Α) |–> Š), the set of data structures such that for any α in Α where α is a human being, there is a record or row σ in Š that represents that human being.

A record data structure being a conglomeration of fields, each of which can symbolically represent some attribute of a larger whole, then we might project additional attributes of the human being, such as their name and identifier, to particular fields within the record. If σ is the particular record structure representing a particular human being, α, then the meaning (values) of the attributes of that person could be associated with the fields, f1..fn, of that record through attribute-level projections, ψ1..ψn for attributes 1 .. n.

To represent a particular person, first we would project the reference to the person to a particular row, Þ(α) |–> σ, then we would also project the attribute facts about that person onto the individual fields of that row:

ψ1(α.1) |–> σ.f1

ψn(α.n) |–> σ.fn

Projection onto Relational Structure

When modeling a domain for incorporation into computer software, the modeler’s task is to define a set of structures which software can be written to manipulate. When that software is to use relational database management systems, then the modeler will first project the domain concepts onto abstract relational structures defined over “tuples”. These abstract structures have a well-defined mathematical nature which if followed provides very powerful manipulations. The developer projects meaning onto relations in a conventional way, such as by defining a relation of attributes to represent “PERSON” – or the set of persons, and another relation of attributes to represent “EMPLOYEE” – or the set of persons who are also employees. Having defined these relational sets, the relational algebra permits various mathematical operations/functions to be applied, such as “JOIN” and “INTERSECTION”. These functions have strictly defined properties and well-defined results over arbitrary tuples. The software developer having projected meaning onto the individual relations, he is also therefore able to project meaning on the outcomes of these operations which can then be used to manipulate large sets of data in an efficient, and semantically correct way.

As the developer creates the software however, they must keep in mind what these functions are doing on two levels, at the level of the set content and at the level of the represented domain (the referent of the sets and manipulations). Thus the intersection of the PERSON and EMPLOYEE relations should produce the subset of tuples (records, etc.) which has its own meaning derived from the initial projected meaning of the original sets. Namely, this intersection represents the set of PERSONS who are also EMPLOYEES, (which is the same, alternatively, as the set of EMPLOYEES who are also PERSONS). This is an important point about software: the meaning is not simply recorded in the data structure but the manipulations of the data by the computer themselves have specific connotations and implications on the meaning of data as it is processed.

Representational Redundancy

As a typical practice in the projection of information onto data structures within the relational model, there will usually be a repetition of the information projected onto more than one symbol. In particular, the reference to the identity of a single person will be represented both by the mere existence of a single row in the table, and also by a subset of fields on the row which the software developers have chosen (and which the software enforces) for this purpose. In other words, under common software development practices, each record/row as a conglomerate entity will represent a single person. In addition, there will be k attributes (1 <= k <= n) on that record structure whose values in combination also represent that same individual. These k attributes make up the “primary key” of the data structure. The software developer will use and repeat these columns on multiple data structures to permit additional concepts regarding the relationship between that person and other ideas also being recorded. For example, a copy of one person record’s primary key could be placed on another person record and be labelled “spouse”. The attributes which make up the primary key often have less mechanical meanings as well (for example, perhaps the primary key for our person includes the name attribute. As part of the primary key, the name value of the person merely helps to reference that person. It also in its own right represents the name of the person.

How Meaning Attaches to Data Structures: A Summary

What follows is a high level summary of how humans attach meaning to various kinds of data structures within a computer. It will serve as a good baseline account, though certainly not an exhaustive one, providing a model upon which more detailed dicussion can begin. 

 Background Terminology

Computer systems provide functionality to support the performance and record of business processes. They do that through three inter-related features: DATA, LOGIC, and PRESENTATION. The presentation consists of information displays permitting both an information visualization aspect and an information capture aspect. The logic consists of several aspects, much of it having to do with support of the presentation and manipulation of displays, but also a lot of it having to do with creation, transformation and storage of data. Data consists of sets of symbols constructed in a systematic, regular fashion using a set of data structures. Different data structures are constructed to represent different aspects of the recorded activity. It is in the relationships between the macro and micro structures where the specific detailed information captured.generated by the business process resides. By following a codified, rigid construction of its data structures, the computer system is able to record multiple recurring instances of similar events. Through the development of fixed transformations using program logic, the computer system is able to make routine, conventional conclusions about those events or observations, and it is able to maintain and retain those observations virtually indefinitely.
Data is maintained and stored in DATA STRUCTURES. The more regular these data structures are, the more easily they are interpreted by a broad audience of software developers. In most situations, the PRESENTATION of the data captured by a system to the end user of that system is in a more directly understandable form than the way that information is stored in the computer.  (This statement is not only trivially true, but in a very deep sense too, since the computer actually stores everything using more and more complex sequences of binary digits. That’s a different subject than our current presentation.)  The data structures within the computer system typically exist in two, simultaneous forms, one intended to support human reasoning (through what is often called a “logical”, “abstract” or “conceptual” model) and one supporting manipulations by the computer. Most software developers today strictly deal with the abstract model of the data for design, coding, and discussion. (There are still some developers working in assembly level code, but even that is at a more abstract level than the actual electro-mechanical machinations of the actual hardware!)
An obvious observation, at least on its face, is that different computer systems will store data representing similar ideas using different structures. We need to keep this in the back of our minds as we progress through the rest of this discussion, but it will be more directly adressed in other entries.
 A final thought concerns sets of data of similar structure, called a POPULATION. A population of data consists of some set of data symbols, all constructed using the same data structure pattern which represents a set of similar ideas. The classification of populations of data structures applies to the DATA portion of systems, represents an analogous classification of sets of observed events external to the computer system, and is affected by and affecting the LOGIC and PRESENTATION portions of the computer system. A more detailed definition of the notion of a “population” will also be treated in separate sections.

Commonalities of Structure

Many computer systems, especially those built in support of business (or other human activity) processes, are constructed using a conventional system of abstract data structures. (When I say they are “conventional” what I mean is that the majority of software developers follow conventional patterns for the construction of data structures to represent their idiosynchratic subject areas.) Whether these structures are called “objects”, “tables”, “records”, or something else, they typically take the form of a heterogenous collection of smaller structures grouped together into regular conglomerations. Instances or examples of the larger collections of data structures will each be said to “represent” individual intances of some real-world conglomerate. Each of the individual component element structures of these conglomerations will each be said to represent the individual attributes or characteristics of the real-world conglomerate object. In order to permit efficient processing by the computer,   instances of similar phenomenon will be represented by the same kind of conglomeration.
Typically, business systems will be based on a data structure called a RECORD.  Records consist of a series of “attribute data structures” all related in some fashion to each other. (A more complex structure called an “object” still has record-like attributes combined together to represent a larger whole, the nuances and variation of object-based representation is a subject for later.)  Each RECORD will stereotypically symbolize one instance of a particular concept. This could be a reference to and certain observed details of a real-world object, or it could be something more ephemereal like observations of an event. For example, one “PERSON” record would represent a single individual person.
RECORDS themselves consist of individually defined data elements or FIELDS. Each RECORD of a particular type will share the same set of FIELDS. Each FIELD will symbolize one kind of fact about the thing symbolized by the RECORD. For example, a NAME field on a PERSON record will record what the represented individual’s name is, at least as it was at the time the record was created. 
The set of all records within a system having the same structure will typically be collected and stored together, often in a data structure called a TABLE. Each TABLE will symbolize the set of KNOWN INSTANCES of whatever type of thing each record represents. TABLES are also described as having ROWS and COLUMNS. Each row of a table is one RECORD. The set of shared element-attribute structures across the set of  rows can be described as the “columns” of the table. Each column represents the set of all instances of a FIELD in the table, in other words, the same field across all records. Tables are a commonly used data structure because they readily support interpretation using relational algebra and set theoretic operations, as well as being easily presented and understood both by human and computer.  

Basic Data Structures and Their Relationships

The nomenclature of “record”, ” table”, “row”, “column” and “fields” describes the construction building blocks of an abstract syntactic medium whose usage permits humans to represent complex concepts within the computer system. By assigning names to various collections and combinations of these generic structures, humans project meaning onto them. Using diagrams called “data models”, a short hand of sorts allows the modeler to describe how the generic tables and fields relate to each other and what these relationships signify in the external world. These models also, by virtue of the typified short hand they use, allows for the generation of computer logic that can be applied to a database to support certain standard operations and manipulations of the data generated by a computer system.

Traditional data modeling results in the creation of a data dictionary which relates each structural element to a particular kind of concept. Every structure will be given a name, and if the developers are diligent, these can be associated with more fully realized text descriptions as well. Some aspects of the data structures are not described, at least typically, within a data model, such as populations or subsets of records with similar structures.

Traditional data dictionary entries record name and description of the set of all structures contained in a table. Using a set of structures to represent a set or collection of similar objects is itself a symbolic action. So not only does each row in a table represent one instance of some type of thing, and each column represents one observed (or derived) fact or attribute of that instance, but the collection of all instances of these row data structures also represents the logical set or population of these things.

The strategy for applying meaning to these data structures begins when the decision is made to treat the entirety of each record as the representation of a member of a population of like things. Being similar, then, a set of fields is conceived to capture various detailed observations regarding the things. These fields are intended to capture details about both how each thing is different from the other things in the collection, but also how different things may share similarities. Much of the business logic of the application system will be consumed by the comparisons between individual things, and the mathematical derived counts (and other metrics) of those sets of things (and of subsets within). Using the computer to compare the bit sequences contained in each field, the computer will indicate whether these contents are the same or different between different instances. Humans will then interpret the results of these comparisons by projecting the conclusion out of the computer and into the conceptual world.

For example, let’s say that we have defined the computer sequence “10101010” to represent a reference to a specific person, “Julie Smith”. If we take two different instances of bit sequences and compare them in the computer, the computer will tell us if they are the same or not. As humans, we would then interpret the purely electro-mechanical result which the computer calculated that “10101010” and “10101010” are the same as an indication that the two instances of these sequences represent the same specific person. Likewise, we would interpret a computer result indicating that two bit sequences were not the same as an indication that different people were being referred to.  This type of projection of meaning from mechanical result to logical inference is fundamental to the way humans use computers.

The specific number of fields and their bit sequence representations (data types)  that are developed within a computer application is entirely dependent on the complexity of the problem domain and the attributes of the objects required to reason over that domain. However, no matter how simple or complex, it is the projection of meaning onto the representation of these attributes in the computer and the projection of an interpretation onto the results of the computer comparisons of the physical representations which makes the computer the powerful engine that it is in our society.

How Row Subsets Represent Subpopulations
How Row Subsets Represent Subpopulations

 

Brass Tacks and Comparability

So I thought I should try to explain “comparability” very simply. Reading my previous posts, which were derived from larger texts, I spend a lot of time saying a lot of generalities, and I think the main point is getting missed. So here’s me getting down to brass tacks on the subject.

A computer CPU is a very basic electrical device. Send it a stream of electrons and a command to “add”, and it returns another stream of electrons representing a purely “mechanical” (i.e., unintelligent) electrical result. That CPU doesn’t know anything about semantics, or whether the switches and gates it opens and closes should appropriately be applied to those particular data streams. It just does what it was designed to do given that particular sequence of electron streams. If the streams are comparable before they get to the CPU, then the output will be meaningful. If they are not comparable, then the output (and being a CPU, there will be some output) will not be meaningful.

So the job of the software is to manipulate each symbol before presenting it to the CPU. In particular, the software needs to take each symbol and replace it with one that MEANS the same as the original symbol, but which will present itself to the CPU as COMPARABLE to the other symbols.

Comparability has to be put into the computer, through the software, by a human being. In particular, it is the human who understands when one data stream is not comparable to another, and it is the human being who writes the code to change one stream so that it becomes comparable to the other.

So what really are we talking about? Let me make a non-computer example to show the point.

2 + 00000010 = IV

If I take a pencil and write the above string of characters on a piece of paper, and show it to another computer programmer, after a few moments, I would expect that person to agree that this is a correct mathematical statement

 two plus two equals four

Part of the success of the person in understanding the original statement is that they are able to parse each symbol in the string, interpret the MEANING of each symbol, then translate each into COMPARABLE numeric ideas.

If the computer CPU could experience each symbol as I’ve written it (let’s agree that each of the symbols depicted here would have similar diversity of structure in the computer as they do here on the page), then we can immediately grasp what comparability is. The CPU does not know what the symbols mean, it cannot make the interpretation just by looking at the symbols as they are presented and come to the same conclusion as the human. 

If we look at what I, the human did, to provide you, the reader, with a more readable version of the equation, I replaced each symbol with another one that meant the same, but which appeared as mutually comparable symbols:

  • 2   –>  two
  • +  –>  plus
  • 00000010  –>  two
  • =  –>  equals
  • IV  –>  four

Before the CPU can compare the symbol “2” to the symbol “00000010”, they must both be replaced with two other symbols, each with the standard interpretation of “two”. These new symbols must be structured to flow through the CPU in such a way that their very structure is modified by the CPU to create a third symbol whose standard interpretation has the meaning “four”. The “plus” symbol must be translated into the CPU’s “ADD” instruction, and the “equals” symbol is represented by the stream of electricity leaving the CPU with the resulting symbol.

Is MDM An Attempt to Reach “Consensus Gentium”?

Consensus gentium

An ancient criterion of truth, the consensus gentium (Latin for agreement of the peoples), states “that which is universal among men carries the weight of truth” (Ferm, 64). A number of consensus theories of truth are based on variations of this principle. In some criteria the notion of universal consent is taken strictly, while others qualify the terms of consensus in various ways. There are versions of consensus theory in which the specific population weighing in on a given question, the proportion of the population required for consent, and the period of time needed to declare consensus vary from the classical norm.*

* “Consensus theory of truth”, Wikipedia entry, November 8, 2008.

The Data Thesaurus

October 25, 2005

 So much of IT’s best practices are taken for granted that no one ever asks if there might be a better way. An example of this is in the area of data standards, enterprise data modeling, and Master Data Management (MDM). The core idea of these initiatives is to try to create a single data dictionary in which every concept important to the enterprise is recorded once, with a single standardized name and definition.

The ideal promoted by this approach is that everyone who works with data in the organization will be much more productive if they all follow one naming convention, and if every data item is documented only once. Sounds logical and practical, and yet when we look around for examples of organizations who have managed to successfully create such a document, complete it for ALL of their systems, even commercial software applications, and then who have kept it maintained and complete for more than a year or two, we find very few. In fact in my experience, which has included a number of valiant efforts, I have found no examples.

When one digs into the anecdotal reasons why such success seems so rare, some mixture of the following statements are often heard:

  1. The company lost its will, the sponsor left and so they cut the budget.
  2. It took too long, the business has redirected the staff to focus on “tactical” efforts with short return on investment cycles.
  3. Even after all that work, no one used it, so it was not maintained.
  4. We were fine until the merger, then we just haven’t been able to keep up with the document and the systems integration/consolidation activities.
  5. Our division and their division just never agreed.
  6. We got our part done, but that other group wouldn’t talk to us.

With ultimate failure at the enterprise level the more common experience, it’s surprising that no one involved in the performance and practice of data standardization has questioned what might really be going on. Lots of enterprises have had successes within smaller efforts. Major lines of business may successfully establish their own data dictionaries for specific projects. Yet very few, if any, have succeeded in translating these tactical successes into truly enterprise-altering programs.

What’s going on here is that the search for the “consensus gentium” as the Romans called it, the universal agreement on the facts and nature of the world by a group of individuals, is a never-ending effort. Staying abreast of the changes in the world that affect this consensus is increasingly impossible, if it ever was possible.

 The point here is that IT and the enterprise needs to stop trying to create a single universal dictionary. It must be recognized that such a comprehensive endeavor is an impossible task for all but the most extravagantly financed IT organizations. It can’t be done because the different contexts of the enterprise are constantly morphing and changing. Keeping abreast of changes costs a tremendous amount in both time and effort, and dollars. Proving an appropriate return on investment for such an ongoing endeavour is problematic, and suffers from the problem of diminishing returns.

 A better approach must be out there. One that takes advantage of the tactical point solutions that most enterprises seem to succeed with, while taking into account the practical limitations imposed by the constant press of change that occurs in any “living” enterprise. This blog attempts to document first-principles affecting the entire endeavor, and will build a case based on the human factors which create the problem in the first place.

 A better approach?

Why not build data dictionaries for individual systems or even small groups (as is often the full extent attempted and completed in most organizations). But instead of trying to extend these point solutions into a universal solution, take a different approach, namely the creation of a “data thesaurus” in which portions of each context are related to each other as synonyms, but only as needed for some particular solution. This thesaurus would track the movement of information through the organization by mapping semantics through and across changes in the “syntactics” of the data carrying this information. The thesaurus would need to track the context of a definition, and that definition would be less abstract and more detailed than those created by the current state of the practice. Links across contexts within the organization would be filled in only as practicality required, as the by-product of data integration projects or system consolidation efforts.

 What’s wrong with the data dictionary of today:

  1. obtuse naming conventions (including local standards and ISO)
  2. abstract data structures that have lost connection with actual data structures
  3. only one name for a concept, when different contexts may have their own colloquialisms – making it hard for practitioners to find “their data”, and even causing the introduction of additional entries for synonyms and aliases as if they were separate things
  4. abstracted or generalized definitions reflecting the “least common denominator” and losing the specificity and nuance present in the original contexts
  5. loss of variations and special cases
  6. detachment from modern software development practices like Agile, XP and even SOA

A Parable for Enterprise Data Standardization (as practiced today)

The enterprise data standard goal of choosing “one term for one concept with one definition” would be the same thing as if the United Nations convened an international standards body whose charter would be to review all human languages and then select the “one best” term for every unique concept in the world. Selection, of course, would be fairly determined to ensure that the term that “best captures” the concept, no matter what the original language was in which the idea was first expressed, would be the term selected. Besides the absurd nature of such a task, consider the practical impossibility of such a task.

First, getting sufficient representation of the world’s languages to make the process fair would require a lot of time. Once started, think of the months of argument, the years and decades that would pass before a useful body of terms would be established and agreed upon. Consider also that while these eggheads were deliberating, life around them would continue. How many new words or concepts would be coined in every language before the first missives would come out of this body? Once an initial (partial) standard was chosen, then the proselytizing would begin. Consider the difficult task of convincing the entire world to stop using the terms of their own language. How would the sale be made? Appealing to some future when “everyone will speak the same language” thus eliminating all barriers to communication most likely. As a person in this environment, how do you learn all of those terms – and remember to use them?

The absurdity of this scenario is fairly clear. Then why do so many data standardization efforts approach their very similar problem in the same way? The example above may be extreme, and some will say that I’ve exaggerated the issue, but that’s just the point I’m trying to make. When one talks with the practitioners of data standardization efforts, they almost always believe that the end goal they are striving for is nothing less than the complete standardization of the enterprise. They may realize intellectually that the job may never be finished, but they still believe that the approach is sound, and that if they can just stay at it long enough, they’ll eventually attain the return on investment and justify their long effort.

If the notion of the UN attempting a global standardization effort seems absurd, than why is the best practice of data standardization the very same approach? If we create a continuum for the application of this approach (see figure) starting at the very smallest project (perhaps the definition of the data supporting a small application system used by a subset of a larger enterprise), and ending at this global UN standardization effort, one has to wonder where along this scale does the practical success of the small effort turn into the absurd impossibility of the global effort? If we choose a point on this continuum and say “here and no further” then no doubt arguments will ensue. Probably, there will be individuals who find the parable above to not be ridiculous. Likewise, there will be others who believe that trying any standardization is a waste of time. Others might try to rationally put an end point on the chart at the point representing their current employer. These folks will find, however, that their current employer merges with another enterprise in a few months, which then raises the question is the point of absurdity further out now, at the ends of the combined organization?

Where Is The Threshold of Absurdity in Data Standardization?

Where Is The Threshold of Absurdity in Data Standardization?

Myself, I believe in being practical, as much as possible. The point of absurdity for me is reached whenever the standardization effort becomes divorced from other initiatives of the enterprise and becomes its own goal. When the data standardization focuses on the particular problem at hand, then the return on the effort can be justified. When data standardization is performed for its own sake, no matter how noble or worthy the sentiment expressed behind the effort, then it is eventually going to overextend its reach and fail.

If we all agree that at SOME point on the continuum, attempting data standardization is an absurd endeavor, then we must recognize that there is a limit to the approach of trying to define data standards. The smaller the context, the more the likelihood of success, and the more utility of the standard to that context. Once we have agreed to this premise, the next question that should leap to mind is: Why don’t our data dictionaries, tools, methods, and best practices record the context within which they are defined? Since we agree we must work within some bounds or face an absurdly huge task, why isn’t it clear from our data dictionaries that they are meaningful only within a specific context?

The XML thought leaders have recognized the importance of context, and while I don’t believe their solution will ultimately solve the problems presented by the common multi-context environments we find ourselves working in, it is at least an attempt. This construct is the “namespace” used to unambiguously tie an XML tag to a validating schema.

Data standards proponents, and many data modelers have not recognized the importance and inevitability of context to their work. They come from a background where all data must be rationalized into a single, comprehensive model, resulting in the loss of variation, ideosyncracy and colloquialism from their environments. These last simply become the “burden of legacy systems” which are anathema to the state of the practice.

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