YES Problem: not(x) -> if(x,false(),true()) and(x,y) -> if(x,y,false()) or(x,y) -> if(x,true(),y) implies(x,y) -> if(x,y,true()) =(x,x) -> true() =(x,y) -> if(x,y,not(y)) if(true(),x,y) -> x if(false(),x,y) -> y if(x,x,if(x,false(),true())) -> true() =(x,y) -> if(x,y,if(y,false(),true())) Proof: Bounds Processor: bound: 3 enrichment: roof automaton: final states: {1} transitions: not0(1) -> 1* if0(1,1,1) -> 1* false0() -> 1* true0() -> 1* and0(1,1) -> 1* or0(1,1) -> 1* implies0(1,1) -> 1* =0(1,1) -> 1* if1(1,1,1) -> 1* false1() -> 1* true1() -> 1* not1(1) -> 1* true2() -> 1* if2(1,1,1) -> 1* false2() -> 1* true3() -> 1* problem: Qed