Categories and General Algebraic Structures with Applications, cilt.13, sa.1, ss.125-141, 2020 (ESCI, Scopus)
The aim of this paper is to introduce the notion of cat1−groupoids which are the groupoid version of cat1−groups and to prove the categorical equivalence between crossed modules over groupoids and cat1−groupoids. In section 4 we introduce the notions of crossed squares over groupoids and of cat2−groupoids, and then we show their categories are equivalent. These equivalences enable us to obtain more examples of groupoids.