fof(ax_D4,axiom,(![A,B,C,D]:((point(A)&point(B)&point(C)&point(D)&cop(A,B,C,D))=>(?[P]:(plane(P)&inc_po_pl(A,P)&inc_po_pl(B,P)&inc_po_pl(C,P)&inc_po_pl(D,P)))))).
