# KACBinTableConstraint¶

class KACBinTableConstraint : public KConstraint

This class implements a generic class for propagation of any binary constraint by local 2-consistency (arc consistency). Two algorithms (AC3 and AC2001) are available for propagation of the constraint.

```// Example : X == Y + 1
KProblem p(...);
KIntVar X(p,"X",0,4);
KIntVar Y(p,"Y",0,4);

// truth table of constraint X == Y + 1 for X in [0..4] and Y in [0..4]

//   |0|1|2|3|4|
// -------------
// 0 |0|1|0|0|0|
// 1 |0|0|1|0|0|
// 2 |0|0|0|1|0|
// 3 |0|0|0|0|1|
// 4 |0|0|0|0|0|
// -------------

bool ** truthTable;
truthTable = new bool*[X.getSup()];
for (int i=0; i < 5; ++i) {
truthTable[i] = new bool[Y.getSup()];
std::memset(truthTable[i],false,Y.getSup() * sizeof(bool));
}
truthTable[1][0] = true; // if X = 1 and Y = 0 then X == Y + 1 is satisfied
truthTable[2][1] = true; // if X = 2 and Y = 1 then X == Y + 1 is satisfied
truthTable[3][2] = true; // if X = 3 and Y = 2 then X == Y + 1 is satisfied
truthTable[4][3] = true; // if X = 4 and Y = 3 then X == Y + 1 is satisfied

p.post(KACBinTableConstraint(X,Y,truthTable,KACBinTableConstraint::ALGORITHM_AC2001,"X == Y + 1"))
```

See
Since

2016.1

Public Types

enum acAlgorithms

Arc-consistency algorithms for binary table constraint.

Values:

enumerator ALGORITHM_AC3
enumerator ALGORITHM_AC2001

Public Functions

KACBinTableConstraint(KIntVar &v1, KIntVar &v2, bool **truthTable, int acAlgorithm = ALGORITHM_AC2001, const char *name = 0)

Main constructor

Parameters
• v1 – the first variable of the constraint

• v2 – the second variable of the constraint

• truthTable – is the truth table of the constraint

• acAlgorithm – ALGORITHM_AC2001 (default value) for propagation by the AC2001 algorithm

• acAlgorithm – ALGORITHM_AC3 for propagation by the AC3 algorithm

• name – label for pretty printing of the constraint

KACBinTableConstraint(const KACBinTableConstraint &toCopy)

Copy Constructor.