(VAR N M X V1 V2 X1 X2 X3) (RULES a__U11(tt,N) -> mark(N) a__U21(tt,M,N) -> s(a__plus(mark(N),mark(M))) a__and(tt,X) -> mark(X) a__isNat(0) -> tt a__isNat(plus(V1,V2)) -> a__and(a__isNat(V1),isNat(V2)) a__isNat(s(V1)) -> a__isNat(V1) a__plus(N,0) -> a__U11(a__isNat(N),N) a__plus(N,s(M)) -> a__U21(a__and(a__isNat(M),isNat(N)),M,N) mark(U11(X1,X2)) -> a__U11(mark(X1),X2) mark(U21(X1,X2,X3)) -> a__U21(mark(X1),X2,X3) mark(plus(X1,X2)) -> a__plus(mark(X1),mark(X2)) mark(and(X1,X2)) -> a__and(mark(X1),X2) mark(isNat(X)) -> a__isNat(X) mark(tt) -> tt mark(s(X)) -> s(mark(X)) mark(0) -> 0 a__U11(X1,X2) -> U11(X1,X2) a__U21(X1,X2,X3) -> U21(X1,X2,X3) a__plus(X1,X2) -> plus(X1,X2) a__and(X1,X2) -> and(X1,X2) a__isNat(X) -> isNat(X) )