Approximate Hagemann-Mitschke co-operations
arXiv:1305.1115 · doi:10.1007/s10485-013-9359-y
Abstract
We show that varietal techniques based on the existence of operations of a certain arity can be extended to n-permutable categories with binary coproducts. This is achieved via what we call approximate Hagemann-Mitschke co-operations, a generalisation of the notion of approximate Mal'tsev co-operation. In particular, we extend characterisation theorems for n-permutable varieties due to J. Hagemann and A. Mitschke to regular categories with binary coproducts.
11 pages. Dedicated to George Janelidze on the occasion of his sixtieth birthday