## Functions

Functions should be considered as ACTIONS performed on some data input that results in some other data output.

Typically, they will represent the application of logical, mathematical or other operations on some set of data.

The effect of the function on the input data may include changes to either the data structure or the concept represented by that input, or could effect changes to both the sign and concept at the same time.

In the Metamorphic Modeling methodology, when a function is written in text form (as opposed to as depicted in graphical form), it appears in a logical tautology, as follows:

f(A) = B

What does the function statement “mean”? What does the computer “understand” from it? To conclude that the computer should understand the left side of the statement to “mean” the same thing as the right side of the statement is a mistake. Since any function can be used in this statement, the proper interpretation is that the right side is derived from the left. Function Types and Diagram Icons

Functions can be viewed as both operations manipulating data and as logical statements in the “logic” of the application system.

Logic languages, like Prolog, and even OWL, for example, represent concepts as logical predicates, and relationships between concepts as predicates with variables.

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1. […] does this trick by applying various “functions” to the symbols. These functions may affect both the structure […]