Subversion Repositories programming

/* digital logic circuit */
/*
      +-----+
A ----|     |
      | and |--not---+
B ----|     |        |   +-----+
      +-----+        +---|     |
                         | and |--- Z
      +-----+        +---|     |
C ----|     |        |   +-----+
      | or  |--not---+
D ----|     |
      +-----+
*/

bit(0).
bit(1).

and(0,0,0).
and(0,1,0).
and(1,0,0).
and(1,1,1).

or(0,0,0).
or(0,1,1).
or(1,0,1).
or(1,1,1).

inv(0,1).
inv(1,0).

circuit(A,B,C,D,Z) :- bit(A),bit(B),bit(C),bit(D),
                      and(A,B,X),
                      or(C,D,Y),
                      inv(X,XBAR),
                      inv(Y,YBAR),
                      and(XBAR,YBAR,Z).