LaTeX-examples/documents/Programmierparadigmen/scripts/prolog/fibonacci2.pl

fib(0,0).
fib(1,1).
fib(X,Y) :- X>1,
    X1 is X-1, X2 is X-2,
    fib(X1,Y1), fib(X2,Y2),
    Y is Y1+Y2.