Edge-Colouring Pairs of Binary Trees: Towards a Concise Proof of the Four-Colour Theorem of Planar Maps.

Alan Gibbons Paul Sant Edge-Colouring Pairs of Binary Trees: Towards a Concise Proof of the Four-Colour Theorem of Planar Maps. 25-39 2002 conf/mfcs/2002 MFCS http://link.springer.de/link/service/series/0558/bibs/2420/24200025.htm db/conf/mfcs/mfcs2002.html#GibbonsS02