matka(anna, ela).
matka(anna, ola).
matka(manna, anna).

member(X,[X|_]).
member(X,[_|T]):-member(X,T).
remove(X,[],[]).
remove(X,[X|T],T1):-remove(X,T,T1).
remove(X,[Y|T],[Y|T1]):-X =\= Y,remove(X,T,T1).
split([^,L1,L2],L1,L2).
alpha([^,_,_]).
onestep(LF,[X1,X2|LTemp]):-member(X,LF),remove(X,LF,LTemp),alpha(X),split(X,X1,X2).