[ Reference Manual | Alphabetic Index ]# library(ic_global_gac)

Library of global constraints which achieve generalized arc consistency
## Predicates

**alldifferent(+L)**
- GAC version of alldifferent
**alldifferent_matrix(+Matrix)**
- Constrain the rows and columns of Matrix to be different values
**gcc(++Bounds, +Vars)**
- Constrain the cardinality of each Value specified in Bound's gcc(Low,High,Value) to be between Low and High in Vars
**gcc_matrix(++RowBounds, ++ColBounds, +Matrix)**
- Constrain the cardinality of values taken in the rows and columns of Matrix as specified by RowBounds and ColBounds, respectively
**inverse(+Succ, +Pred)**
- Constrains elements of Succ to be the successors and Pred to be the predecessors of nodes in a digraph
**lex_le(+List1, +List2)**
- List1 is lexicographically less or equal to List2
**lex_lt(+List1, +List2)**
- List1 is lexicographically less than List2
**matching(+L, -K)**
- Get a matching between a list of domain variables and their possible values
**same(+Vars1, +Vars2)**
- Vars1 and Vars2 are constrained to be a permutation of each other in the values taken by the variables.
**sequence(+Low, +High, +K, +ZeroOnes)**
- The number of occurrences of the value 1 is between Low and High for all sequences of K variables in ZeroOnes
**sequence(+Low, +High, +K, +Vars, ++Values)**
- The number of values taken from Values is between Low and High for all sequences of K variables in Vars.

## Reexports

## Other Exports

**export portray(update_alldifferent / 4, tr_global_gac_out / 2, [goal])**

## Description

This library is intended for global constraints for which GAC (generalized arc consistency, also called hyper arc consistency, or domain consistency) is maintained. The first example is a version of the alldifferent constraint which performs more pruning than the bound consistent version in the ic_global library.
## About

**Status: **prototype
**Author: **H. Simonis, 4C, University College Cork
**Copyright © **2008, H. Simonis, 4C, University College Cork
**Date: **2008

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