20.500.12556/RUP-21708 Coverings of general digraphs Krovi splošnih digrafov A unified theory of covering projections of graphs and digraphs is presented as one theory by considering coverings of general digraphs, where multiple directed and undirected edges together with oriented and unoriented loops and semiedges, are allowed. It transpires that coverings of general digraphs can display certain pathological behaviour since the naturally defined projections of their underlying graphs may not be coverings in the usual topological sense. Consequently, homotopy does not always lift, although the unique walk lifting property still holds. Yet, it is still possible to grasp such coverings algebraically in terms of the action of the fundamental monoid. This action is permutational and has certain nice properties that monoid actions in general do not have. As a consequence, such projections can be studied combinatorially in terms of voltages. The problem of isomorphism and equivalence, and in particular, the problem of lifting automorphisms, is treated in depth. All known results about covering projections of graphs are simple corollaries of just three general theorems. mixed graph general digraph dart covering projection voltage homotopy monoid action lifting automorphisms mešani graf splošni digraf grafoid puščica krovna projekcija napetost homotopija monoidno delovanje dvig avtomorfizmov. true false true Založba Univerze na Primorskem Angleški jezik Slovenski jezik Neznano 2025-09-10 13:46:29 2025-09-10 13:46:29 2025-10-24 23:20:31 0000-00-00 00:00:00 2025 0 0 30 str. no. 3, [article no.] P3.09 Vol 25 2025 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 2025-06-20 51 1855-3974 10.26493/1855-3974.3267.7d4 200176899 AMC_Malnic,Zgrablic_2025.pdf AMC_Malnic,Zgrablic_2025.pdf 1 755CE594797AAA2ECF98B2DBD15FEC6F 8739a2143f5fb06f80dd092f92d60170313b41e157f308d2a3d5615788298860 f6824d0b-8e3b-11f0-8f0b-005056ac49c0 https://repozitorij.upr.si/Dokument.php?lang=slv&id=31538 Založba Univerze na Primorskem 0 0 0