5.127. eq

DESCRIPTIONLINKS
Origin

Arithmetic.

Constraint

𝚎𝚚(𝚅𝙰𝚁1,𝚅𝙰𝚁2)

Synonym

𝚡𝚎𝚚𝚢.

Arguments
𝚅𝙰𝚁1𝚍𝚟𝚊𝚛
𝚅𝙰𝚁2𝚍𝚟𝚊𝚛
Restriction
Purpose

Enforce the fact that two variables are equal.

Example
(8,8)

The 𝚎𝚚 constraint holds since 8 is equal to 8.

Symmetries
  • Arguments are permutable w.r.t. permutation (𝚅𝙰𝚁1,𝚅𝙰𝚁2).

  • All occurrences of a value in 𝚅𝙰𝚁1 or 𝚅𝙰𝚁2 can be renamed to any unused value.

Systems

eq in Choco, rel in Gecode, xeqy in JaCoP, #= in SICStus.

See also

common keyword: 𝚐𝚝, 𝚕𝚝 (binary constraint,arithmetic constraint).

generalisation: 𝚊𝚕𝚕_𝚎𝚚𝚞𝚊𝚕 (equality between more than two variables), 𝚎𝚚_𝚌𝚜𝚝 (𝚌𝚘𝚗𝚜𝚝𝚊𝚗𝚝 added), 𝚎𝚚_𝚜𝚎𝚝 (𝚟𝚊𝚛𝚒𝚊𝚋𝚕𝚎 replaced by 𝚜𝚎𝚝 𝚟𝚊𝚛𝚒𝚊𝚋𝚕𝚎).

implies: 𝚊𝚋𝚜_𝚟𝚊𝚕𝚞𝚎, 𝚐𝚎𝚚, 𝚕𝚎𝚚.

negation: 𝚗𝚎𝚚.

Keywords

constraint arguments: binary constraint.

constraint type: predefined constraint, arithmetic constraint.

filtering: arc-consistency.