There is a relation-algebra tag, which is also used for questions about relational algebra, which is another thing. Operators defined in relation algebra are different than the ones defined on relational algebra. Relational algebra also deals with concepts that relation algebra does not (like fun...

I am going through the definition of a twisted wreath product defined in Dixon and Mortimer's book Permutation groups, which goes as follows. Let $T$ and $K$ be arbitrary groups and let $L \leq K$ together with a specified homomorphism $\phi:L\to \mathrm{Aut}(T)$. Let $R$ be a left transversal fo...