Reflections on and of minor-closed classes of multisorted operations
Lehtonen, Erkko; Pöschel, Reinhard; Waldhauser, Tamás
Algebra Universalis, 79 (2018), Art. 71, 19 pp.
The minor relation of functions is generalized to multisorted functions. Pippenger’s Galois theory for minor-closed sets of functions is extended to multisorted functions and multisorted relation pairs. Reflections of minor-closed sets are again minor-closed, and the effect of reflections on the invariant relation pairs of minor-closed sets of multisorted functions is described.