### 3.7.89. Duplicated variables

A constraint for which the situation where the same variable can occur more than once was considered in order to derive a better filtering algorithm or to prove a complexity result for achieving arc -consistency. Also in the case of the $\mathrm{𝚜𝚝𝚛𝚎𝚝𝚌𝚑}_\mathrm{𝚌𝚒𝚛𝚌𝚞𝚒𝚝}$ constraint, a constraint for which the reformulation duplicates some variables.