Is GAP suited for studying combinatorial structures and finite permutation groups?
GAP is suited very well for computing in combinatorial structures and permutation groups. A small but nevertheless illustrative example given by Stefan Kohl in an answer to a letter to ‘gap-support’ is the investigation of the automorphism group of a graph whose vertices are the cards of a card game called `Duo’ (http://www.mystery-games.com/duocardgame.html) with edges between any two cards that ‘fit together’. The game `Duo’ consists of 4^3 = 64 `normal’ cards each showing a triple (colour, shape, number), where there are four possible colours, shapes and numbers (any possible combination occurs exactly once) and 3*4 = 12 jokers each showing either a colour, a shape or a number. Two `normal’ cards fit together if and only if they coincide in two of their symbols. E.g. (red, square, 1) and (green, square, 1) fit together, but (red, square, 1) and (red, triangle, 3) do not. A joker fits together with a `normal’ card if one of the three symbols of the latter is the joker’s, e.g. the (bl
