2.5.16. Root concept

Constraint C 𝑒𝑛𝑡𝑟𝑦 is derived from constraint C 𝑎𝑙𝑠𝑜 .

EXAMPLE: As an example, the constraint C 𝑒𝑛𝑡𝑟𝑦 = 𝚝𝚛𝚎𝚎_𝚛𝚎𝚜𝚘𝚞𝚛𝚌𝚎 is derived from the constraint C 𝑎𝑙𝑠𝑜 = 𝚝𝚛𝚎𝚎. Given a digraph G, the 𝚝𝚛𝚎𝚎 constraint enforces a partitioning of G by a set of trees in such a way that each vertex of G belongs to one distinct tree. In addition, the 𝚝𝚛𝚎𝚎_𝚛𝚎𝚜𝚘𝚞𝚛𝚌𝚎 constraint distinguishes resource and task vertices, and enforces each tree to contain exactly one resource vertex.