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Like derived attributes these expression may invoke EXPRESS functions, which may further invoke EXPRESS procedures. The functions and procedures allow formulating complex statements with local variables, parameters and constants - very similar to a programming language. The EXPRESS language can describe local and global rules. For example:
The formal theory of IDEF1X provides both the semantics and a means to precisely express the necessary constraints. A meta model for IDEF1X is given in the adjacent figure. The name of the view is mm. The domain hierarchy and constraints are also given. The constraints are expressed as sentences in the formal theory of the meta model.
Python sets are very much like mathematical sets, and support operations like set intersection and union. Python also features a frozenset class for immutable sets, see Collection types. Dictionaries (class dict) are mutable mappings tying keys and corresponding values. Python has special syntax to create dictionaries ({key: value})
The states of a created conceptual schema are transformed into an explicit mapping, the database schema. This describes how real-world entities are modeled in the database. "A database schema specifies, based on the database administrator 's knowledge of possible applications, the facts that can enter the database, or those of interest to the ...
Constraint programming states relations between variables in the form of constraints that specify the properties of the target solution. The set of constraints is solved by giving a value to each variable so that the solution is consistent with the maximum number of constraints. Constraint programming often complements other paradigms ...
In relational database theory, a functional dependency is the following constraint between two attribute sets in a relation: Given a relation R and attribute sets ,, X is said to functionally determine Y (written X → Y) if each X value is associated with precisely one Y value.
functional – a desired result is declared as the value of a series of function evaluations, uses evaluation of mathematical functions and avoids state and mutable data; logic – a desired result is declared as the answer to a question about a system of facts and rules, uses explicit mathematical logic for programming
Given a set of feature functions {(,)} and a set of constraints {(,)}, defined over an input structure and an output structure , a constraint conditional model is characterized by two weight vectors, w and , and is defined as the solution to the following optimization problem: