female(helle).
female(pernille).
female(marianne).
female(lisbeth).
female(pia).
female(lene).
female(emma).

male(jens).
male(torben).
male(rasmus).
male(lars).
male(jesper).
male(hans).

married(jens, helle).
married(rasmus, marianne).
married(torben, lisbeth).
married(hans, pernille).

motherOf(helle, pernille).
motherOf(helle, torben).
motherOf(marianne, lisbeth).
motherOf(marianne, lars).
motherOf(lisbeth, jesper).
motherOf(lisbeth, pia).
motherOf(pernille, lene).
motherOf(pernille, emma).

diff(X,Y) :- X \== Y.