2.6.8. Hard version

Constraint C 𝑎𝑙𝑠𝑜 is a hard version of constraint C 𝑒𝑛𝑡𝑟𝑦 (i.e., constraint C 𝑒𝑛𝑡𝑟𝑦 is a soft variant of constraint C 𝑎𝑙𝑠𝑜 ).

EXAMPLE: As an example, constraint C 𝑎𝑙𝑠𝑜 = 𝚊𝚕𝚕𝚍𝚒𝚏𝚏𝚎𝚛𝚎𝚗𝚝 is a hard version of constraint C 𝑒𝑛𝑡𝑟𝑦 = 𝚜𝚘𝚏𝚝_𝚊𝚕𝚕𝚍𝚒𝚏𝚏𝚎𝚛𝚎𝚗𝚝, which restricts the minimum number of variables that should be assigned differently in order that all variables take a distinct value.