2.5.19. Specialisation

Denotes the fact that constraint C 𝑎𝑙𝑠𝑜 is a specialisation of constraint C 𝑒𝑛𝑡𝑟𝑦 .

EXAMPLE: As an example, constraint C 𝑎𝑙𝑠𝑜 = 𝚙𝚊𝚝𝚑 is a specialisation of constraint C 𝑒𝑛𝑡𝑟𝑦 = 𝚝𝚛𝚎𝚎. Given a digraph G, the 𝚝𝚛𝚎𝚎 constraint enforces a covering of G by a set of trees in such a way that each vertex of G belongs to one distinct tree. If, in addition, we restrict each vertex to have at most one child we get the 𝚙𝚊𝚝𝚑 constraint.