% Unprogramming a permutation machine
stack([],[],[]) --> [].
stack([push|Instrs],[I|IS],SS) --> stack(Instrs,IS,[I|SS]).
stack([pop|Instrs],IS,[S|SS]) --> [S], stack(Instrs,IS,SS).
% ?- phrase(stack(Instructions, [1,2,3,4,5], []), [1,2,4,3,5], []).
% Instructions = [push, pop, push, pop, push, push, pop, pop, push, pop] .
Monday, 27 October 2008
Subscribe to:
Post Comments (Atom)
1 comment:
Elegant! What permutations does this allow? (Obviously not all of them, since 2^2n < n! for large n.)
Post a Comment