### 3.7.170. Obscure

A constraint for which a better description is needed (i.e., $\mathrm{𝚝𝚠𝚘}_\mathrm{𝚕𝚊𝚢𝚎𝚛}_\mathrm{𝚎𝚍𝚐𝚎}_\mathrm{𝚌𝚛𝚘𝚜𝚜𝚒𝚗𝚐}$), or a constraint for which the definition needs to be checked: the eight topological relations of RCC-8 should be mutually incompatible, which is not the case with the current logic based definitions.