Abian, Alexander Four-coloring of infinite maps. (English) Zbl 0536.05021 Math. Balk. 8, 3-6 (1978). Well-known result concerning four-colourability of planar maps is extended to infinite maps with denumerably many countries. Proof is simple without invoking the compactness of the propositional logic or an ultraproduct construction or topological considerations. Reviewer: J.Fiamčík MSC: 05C15 Coloring of graphs and hypergraphs 05C10 Planar graphs; geometric and topological aspects of graph theory Keywords:four-colourability; planar maps PDFBibTeX XMLCite \textit{A. Abian}, Math. Balk. 8, 3--6 (1978; Zbl 0536.05021)