YES We show the termination of the TRS R: active(and(true(),X)) -> mark(X) active(and(false(),Y)) -> mark(false()) active(if(true(),X,Y)) -> mark(X) active(if(false(),X,Y)) -> mark(Y) active(add(|0|(),X)) -> mark(X) active(add(s(X),Y)) -> mark(s(add(X,Y))) active(first(|0|(),X)) -> mark(nil()) active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z))) active(from(X)) -> mark(cons(X,from(s(X)))) mark(and(X1,X2)) -> active(and(mark(X1),X2)) mark(true()) -> active(true()) mark(false()) -> active(false()) mark(if(X1,X2,X3)) -> active(if(mark(X1),X2,X3)) mark(add(X1,X2)) -> active(add(mark(X1),X2)) mark(|0|()) -> active(|0|()) mark(s(X)) -> active(s(X)) mark(first(X1,X2)) -> active(first(mark(X1),mark(X2))) mark(nil()) -> active(nil()) mark(cons(X1,X2)) -> active(cons(X1,X2)) mark(from(X)) -> active(from(X)) and(mark(X1),X2) -> and(X1,X2) and(X1,mark(X2)) -> and(X1,X2) and(active(X1),X2) -> and(X1,X2) and(X1,active(X2)) -> and(X1,X2) if(mark(X1),X2,X3) -> if(X1,X2,X3) if(X1,mark(X2),X3) -> if(X1,X2,X3) if(X1,X2,mark(X3)) -> if(X1,X2,X3) if(active(X1),X2,X3) -> if(X1,X2,X3) if(X1,active(X2),X3) -> if(X1,X2,X3) if(X1,X2,active(X3)) -> if(X1,X2,X3) add(mark(X1),X2) -> add(X1,X2) add(X1,mark(X2)) -> add(X1,X2) add(active(X1),X2) -> add(X1,X2) add(X1,active(X2)) -> add(X1,X2) s(mark(X)) -> s(X) s(active(X)) -> s(X) first(mark(X1),X2) -> first(X1,X2) first(X1,mark(X2)) -> first(X1,X2) first(active(X1),X2) -> first(X1,X2) first(X1,active(X2)) -> first(X1,X2) cons(mark(X1),X2) -> cons(X1,X2) cons(X1,mark(X2)) -> cons(X1,X2) cons(active(X1),X2) -> cons(X1,X2) cons(X1,active(X2)) -> cons(X1,X2) from(mark(X)) -> from(X) from(active(X)) -> from(X) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: active#(and(true(),X)) -> mark#(X) p2: active#(and(false(),Y)) -> mark#(false()) p3: active#(if(true(),X,Y)) -> mark#(X) p4: active#(if(false(),X,Y)) -> mark#(Y) p5: active#(add(|0|(),X)) -> mark#(X) p6: active#(add(s(X),Y)) -> mark#(s(add(X,Y))) p7: active#(add(s(X),Y)) -> s#(add(X,Y)) p8: active#(add(s(X),Y)) -> add#(X,Y) p9: active#(first(|0|(),X)) -> mark#(nil()) p10: active#(first(s(X),cons(Y,Z))) -> mark#(cons(Y,first(X,Z))) p11: active#(first(s(X),cons(Y,Z))) -> cons#(Y,first(X,Z)) p12: active#(first(s(X),cons(Y,Z))) -> first#(X,Z) p13: active#(from(X)) -> mark#(cons(X,from(s(X)))) p14: active#(from(X)) -> cons#(X,from(s(X))) p15: active#(from(X)) -> from#(s(X)) p16: active#(from(X)) -> s#(X) p17: mark#(and(X1,X2)) -> active#(and(mark(X1),X2)) p18: mark#(and(X1,X2)) -> and#(mark(X1),X2) p19: mark#(and(X1,X2)) -> mark#(X1) p20: mark#(true()) -> active#(true()) p21: mark#(false()) -> active#(false()) p22: mark#(if(X1,X2,X3)) -> active#(if(mark(X1),X2,X3)) p23: mark#(if(X1,X2,X3)) -> if#(mark(X1),X2,X3) p24: mark#(if(X1,X2,X3)) -> mark#(X1) p25: mark#(add(X1,X2)) -> active#(add(mark(X1),X2)) p26: mark#(add(X1,X2)) -> add#(mark(X1),X2) p27: mark#(add(X1,X2)) -> mark#(X1) p28: mark#(|0|()) -> active#(|0|()) p29: mark#(s(X)) -> active#(s(X)) p30: mark#(first(X1,X2)) -> active#(first(mark(X1),mark(X2))) p31: mark#(first(X1,X2)) -> first#(mark(X1),mark(X2)) p32: mark#(first(X1,X2)) -> mark#(X1) p33: mark#(first(X1,X2)) -> mark#(X2) p34: mark#(nil()) -> active#(nil()) p35: mark#(cons(X1,X2)) -> active#(cons(X1,X2)) p36: mark#(from(X)) -> active#(from(X)) p37: and#(mark(X1),X2) -> and#(X1,X2) p38: and#(X1,mark(X2)) -> and#(X1,X2) p39: and#(active(X1),X2) -> and#(X1,X2) p40: and#(X1,active(X2)) -> and#(X1,X2) p41: if#(mark(X1),X2,X3) -> if#(X1,X2,X3) p42: if#(X1,mark(X2),X3) -> if#(X1,X2,X3) p43: if#(X1,X2,mark(X3)) -> if#(X1,X2,X3) p44: if#(active(X1),X2,X3) -> if#(X1,X2,X3) p45: if#(X1,active(X2),X3) -> if#(X1,X2,X3) p46: if#(X1,X2,active(X3)) -> if#(X1,X2,X3) p47: add#(mark(X1),X2) -> add#(X1,X2) p48: add#(X1,mark(X2)) -> add#(X1,X2) p49: add#(active(X1),X2) -> add#(X1,X2) p50: add#(X1,active(X2)) -> add#(X1,X2) p51: s#(mark(X)) -> s#(X) p52: s#(active(X)) -> s#(X) p53: first#(mark(X1),X2) -> first#(X1,X2) p54: first#(X1,mark(X2)) -> first#(X1,X2) p55: first#(active(X1),X2) -> first#(X1,X2) p56: first#(X1,active(X2)) -> first#(X1,X2) p57: cons#(mark(X1),X2) -> cons#(X1,X2) p58: cons#(X1,mark(X2)) -> cons#(X1,X2) p59: cons#(active(X1),X2) -> cons#(X1,X2) p60: cons#(X1,active(X2)) -> cons#(X1,X2) p61: from#(mark(X)) -> from#(X) p62: from#(active(X)) -> from#(X) and R consists of: r1: active(and(true(),X)) -> mark(X) r2: active(and(false(),Y)) -> mark(false()) r3: active(if(true(),X,Y)) -> mark(X) r4: active(if(false(),X,Y)) -> mark(Y) r5: active(add(|0|(),X)) -> mark(X) r6: active(add(s(X),Y)) -> mark(s(add(X,Y))) r7: active(first(|0|(),X)) -> mark(nil()) r8: active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z))) r9: active(from(X)) -> mark(cons(X,from(s(X)))) r10: mark(and(X1,X2)) -> active(and(mark(X1),X2)) r11: mark(true()) -> active(true()) r12: mark(false()) -> active(false()) r13: mark(if(X1,X2,X3)) -> active(if(mark(X1),X2,X3)) r14: mark(add(X1,X2)) -> active(add(mark(X1),X2)) r15: mark(|0|()) -> active(|0|()) r16: mark(s(X)) -> active(s(X)) r17: mark(first(X1,X2)) -> active(first(mark(X1),mark(X2))) r18: mark(nil()) -> active(nil()) r19: mark(cons(X1,X2)) -> active(cons(X1,X2)) r20: mark(from(X)) -> active(from(X)) r21: and(mark(X1),X2) -> and(X1,X2) r22: and(X1,mark(X2)) -> and(X1,X2) r23: and(active(X1),X2) -> and(X1,X2) r24: and(X1,active(X2)) -> and(X1,X2) r25: if(mark(X1),X2,X3) -> if(X1,X2,X3) r26: if(X1,mark(X2),X3) -> if(X1,X2,X3) r27: if(X1,X2,mark(X3)) -> if(X1,X2,X3) r28: if(active(X1),X2,X3) -> if(X1,X2,X3) r29: if(X1,active(X2),X3) -> if(X1,X2,X3) r30: if(X1,X2,active(X3)) -> if(X1,X2,X3) r31: add(mark(X1),X2) -> add(X1,X2) r32: add(X1,mark(X2)) -> add(X1,X2) r33: add(active(X1),X2) -> add(X1,X2) r34: add(X1,active(X2)) -> add(X1,X2) r35: s(mark(X)) -> s(X) r36: s(active(X)) -> s(X) r37: first(mark(X1),X2) -> first(X1,X2) r38: first(X1,mark(X2)) -> first(X1,X2) r39: first(active(X1),X2) -> first(X1,X2) r40: first(X1,active(X2)) -> first(X1,X2) r41: cons(mark(X1),X2) -> cons(X1,X2) r42: cons(X1,mark(X2)) -> cons(X1,X2) r43: cons(active(X1),X2) -> cons(X1,X2) r44: cons(X1,active(X2)) -> cons(X1,X2) r45: from(mark(X)) -> from(X) r46: from(active(X)) -> from(X) The estimated dependency graph contains the following SCCs: {p1, p3, p4, p5, p6, p10, p13, p17, p19, p22, p24, p25, p27, p29, p30, p32, p33, p35, p36} {p51, p52} {p47, p48, p49, p50} {p57, p58, p59, p60} {p53, p54, p55, p56} {p61, p62} {p37, p38, p39, p40} {p41, p42, p43, p44, p45, p46} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: active#(and(true(),X)) -> mark#(X) p2: mark#(from(X)) -> active#(from(X)) p3: active#(from(X)) -> mark#(cons(X,from(s(X)))) p4: mark#(cons(X1,X2)) -> active#(cons(X1,X2)) p5: active#(first(s(X),cons(Y,Z))) -> mark#(cons(Y,first(X,Z))) p6: mark#(first(X1,X2)) -> mark#(X2) p7: mark#(first(X1,X2)) -> mark#(X1) p8: mark#(first(X1,X2)) -> active#(first(mark(X1),mark(X2))) p9: active#(add(s(X),Y)) -> mark#(s(add(X,Y))) p10: mark#(s(X)) -> active#(s(X)) p11: active#(add(|0|(),X)) -> mark#(X) p12: mark#(add(X1,X2)) -> mark#(X1) p13: mark#(add(X1,X2)) -> active#(add(mark(X1),X2)) p14: active#(if(false(),X,Y)) -> mark#(Y) p15: mark#(if(X1,X2,X3)) -> mark#(X1) p16: mark#(if(X1,X2,X3)) -> active#(if(mark(X1),X2,X3)) p17: active#(if(true(),X,Y)) -> mark#(X) p18: mark#(and(X1,X2)) -> mark#(X1) p19: mark#(and(X1,X2)) -> active#(and(mark(X1),X2)) and R consists of: r1: active(and(true(),X)) -> mark(X) r2: active(and(false(),Y)) -> mark(false()) r3: active(if(true(),X,Y)) -> mark(X) r4: active(if(false(),X,Y)) -> mark(Y) r5: active(add(|0|(),X)) -> mark(X) r6: active(add(s(X),Y)) -> mark(s(add(X,Y))) r7: active(first(|0|(),X)) -> mark(nil()) r8: active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z))) r9: active(from(X)) -> mark(cons(X,from(s(X)))) r10: mark(and(X1,X2)) -> active(and(mark(X1),X2)) r11: mark(true()) -> active(true()) r12: mark(false()) -> active(false()) r13: mark(if(X1,X2,X3)) -> active(if(mark(X1),X2,X3)) r14: mark(add(X1,X2)) -> active(add(mark(X1),X2)) r15: mark(|0|()) -> active(|0|()) r16: mark(s(X)) -> active(s(X)) r17: mark(first(X1,X2)) -> active(first(mark(X1),mark(X2))) r18: mark(nil()) -> active(nil()) r19: mark(cons(X1,X2)) -> active(cons(X1,X2)) r20: mark(from(X)) -> active(from(X)) r21: and(mark(X1),X2) -> and(X1,X2) r22: and(X1,mark(X2)) -> and(X1,X2) r23: and(active(X1),X2) -> and(X1,X2) r24: and(X1,active(X2)) -> and(X1,X2) r25: if(mark(X1),X2,X3) -> if(X1,X2,X3) r26: if(X1,mark(X2),X3) -> if(X1,X2,X3) r27: if(X1,X2,mark(X3)) -> if(X1,X2,X3) r28: if(active(X1),X2,X3) -> if(X1,X2,X3) r29: if(X1,active(X2),X3) -> if(X1,X2,X3) r30: if(X1,X2,active(X3)) -> if(X1,X2,X3) r31: add(mark(X1),X2) -> add(X1,X2) r32: add(X1,mark(X2)) -> add(X1,X2) r33: add(active(X1),X2) -> add(X1,X2) r34: add(X1,active(X2)) -> add(X1,X2) r35: s(mark(X)) -> s(X) r36: s(active(X)) -> s(X) r37: first(mark(X1),X2) -> first(X1,X2) r38: first(X1,mark(X2)) -> first(X1,X2) r39: first(active(X1),X2) -> first(X1,X2) r40: first(X1,active(X2)) -> first(X1,X2) r41: cons(mark(X1),X2) -> cons(X1,X2) r42: cons(X1,mark(X2)) -> cons(X1,X2) r43: cons(active(X1),X2) -> cons(X1,X2) r44: cons(X1,active(X2)) -> cons(X1,X2) r45: from(mark(X)) -> from(X) r46: from(active(X)) -> from(X) The set of usable rules consists of r1, r2, r3, r4, r5, r6, r7, r8, r9, r10, r11, r12, r13, r14, r15, r16, r17, r18, r19, r20, r21, r22, r23, r24, r25, r26, r27, r28, r29, r30, r31, r32, r33, r34, r35, r36, r37, r38, r39, r40, r41, r42, r43, r44, r45, r46 Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: active#_A(x1) = max{70, x1 + 7} and_A(x1,x2) = max{141, x1 + 72, x2 + 122} true_A = 26 mark#_A(x1) = max{32, x1 + 29} from_A(x1) = x1 + 71 cons_A(x1,x2) = x1 + 41 s_A(x1) = 41 first_A(x1,x2) = max{311, x1 + 185, x2 + 106} mark_A(x1) = max{71, x1 + 20} add_A(x1,x2) = max{104, x1 + 52, x2 + 83} |0|_A = 106 if_A(x1,x2,x3) = max{x1 + 72, x2 + 151, x3 + 151} false_A = 8 active_A(x1) = max{27, x1} nil_A = 85 precedence: from = mark > true = add > if > mark# > active# = and = cons = |0| > s = first = false = active = nil partial status: pi(active#) = [1] pi(and) = [1, 2] pi(true) = [] pi(mark#) = [1] pi(from) = [1] pi(cons) = [] pi(s) = [] pi(first) = [1, 2] pi(mark) = [] pi(add) = [1, 2] pi(|0|) = [] pi(if) = [1, 2, 3] pi(false) = [] pi(active) = [1] pi(nil) = [] 2. weighted path order base order: max/plus interpretations on natural numbers: active#_A(x1) = x1 and_A(x1,x2) = max{x1 + 31, x2 + 24} true_A = 17 mark#_A(x1) = x1 from_A(x1) = max{50, x1 + 42} cons_A(x1,x2) = 0 s_A(x1) = 41 first_A(x1,x2) = max{5, x1 + 2} mark_A(x1) = 0 add_A(x1,x2) = max{x1, x2} |0|_A = 17 if_A(x1,x2,x3) = max{x1 + 30, x2 + 7, x3 + 15} false_A = 17 active_A(x1) = 0 nil_A = 18 precedence: add = nil > and = true = mark# = s = first = |0| = if = false > active# = from = cons > mark = active partial status: pi(active#) = [1] pi(and) = [2] pi(true) = [] pi(mark#) = [1] pi(from) = [1] pi(cons) = [] pi(s) = [] pi(first) = [] pi(mark) = [] pi(add) = [1, 2] pi(|0|) = [] pi(if) = [3] pi(false) = [] pi(active) = [] pi(nil) = [] The next rules are strictly ordered: p1, p2, p3, p4, p5, p6, p7, p8, p9, p10, p11, p12, p13, p14, p15, p16, p17, p18, p19 We remove them from the problem. Then no dependency pair remains. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: s#(mark(X)) -> s#(X) p2: s#(active(X)) -> s#(X) and R consists of: r1: active(and(true(),X)) -> mark(X) r2: active(and(false(),Y)) -> mark(false()) r3: active(if(true(),X,Y)) -> mark(X) r4: active(if(false(),X,Y)) -> mark(Y) r5: active(add(|0|(),X)) -> mark(X) r6: active(add(s(X),Y)) -> mark(s(add(X,Y))) r7: active(first(|0|(),X)) -> mark(nil()) r8: active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z))) r9: active(from(X)) -> mark(cons(X,from(s(X)))) r10: mark(and(X1,X2)) -> active(and(mark(X1),X2)) r11: mark(true()) -> active(true()) r12: mark(false()) -> active(false()) r13: mark(if(X1,X2,X3)) -> active(if(mark(X1),X2,X3)) r14: mark(add(X1,X2)) -> active(add(mark(X1),X2)) r15: mark(|0|()) -> active(|0|()) r16: mark(s(X)) -> active(s(X)) r17: mark(first(X1,X2)) -> active(first(mark(X1),mark(X2))) r18: mark(nil()) -> active(nil()) r19: mark(cons(X1,X2)) -> active(cons(X1,X2)) r20: mark(from(X)) -> active(from(X)) r21: and(mark(X1),X2) -> and(X1,X2) r22: and(X1,mark(X2)) -> and(X1,X2) r23: and(active(X1),X2) -> and(X1,X2) r24: and(X1,active(X2)) -> and(X1,X2) r25: if(mark(X1),X2,X3) -> if(X1,X2,X3) r26: if(X1,mark(X2),X3) -> if(X1,X2,X3) r27: if(X1,X2,mark(X3)) -> if(X1,X2,X3) r28: if(active(X1),X2,X3) -> if(X1,X2,X3) r29: if(X1,active(X2),X3) -> if(X1,X2,X3) r30: if(X1,X2,active(X3)) -> if(X1,X2,X3) r31: add(mark(X1),X2) -> add(X1,X2) r32: add(X1,mark(X2)) -> add(X1,X2) r33: add(active(X1),X2) -> add(X1,X2) r34: add(X1,active(X2)) -> add(X1,X2) r35: s(mark(X)) -> s(X) r36: s(active(X)) -> s(X) r37: first(mark(X1),X2) -> first(X1,X2) r38: first(X1,mark(X2)) -> first(X1,X2) r39: first(active(X1),X2) -> first(X1,X2) r40: first(X1,active(X2)) -> first(X1,X2) r41: cons(mark(X1),X2) -> cons(X1,X2) r42: cons(X1,mark(X2)) -> cons(X1,X2) r43: cons(active(X1),X2) -> cons(X1,X2) r44: cons(X1,active(X2)) -> cons(X1,X2) r45: from(mark(X)) -> from(X) r46: from(active(X)) -> from(X) The set of usable rules consists of (no rules) Take the monotone reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: s#_A(x1) = max{6, x1 + 4} mark_A(x1) = max{4, x1 + 3} active_A(x1) = max{2, x1 + 1} precedence: s# = mark = active partial status: pi(s#) = [1] pi(mark) = [1] pi(active) = [1] 2. weighted path order base order: max/plus interpretations on natural numbers: s#_A(x1) = x1 + 1 mark_A(x1) = x1 active_A(x1) = x1 precedence: s# = mark = active partial status: pi(s#) = [1] pi(mark) = [1] pi(active) = [1] The next rules are strictly ordered: p1, p2 We remove them from the problem. Then no dependency pair remains. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: add#(mark(X1),X2) -> add#(X1,X2) p2: add#(X1,active(X2)) -> add#(X1,X2) p3: add#(active(X1),X2) -> add#(X1,X2) p4: add#(X1,mark(X2)) -> add#(X1,X2) and R consists of: r1: active(and(true(),X)) -> mark(X) r2: active(and(false(),Y)) -> mark(false()) r3: active(if(true(),X,Y)) -> mark(X) r4: active(if(false(),X,Y)) -> mark(Y) r5: active(add(|0|(),X)) -> mark(X) r6: active(add(s(X),Y)) -> mark(s(add(X,Y))) r7: active(first(|0|(),X)) -> mark(nil()) r8: active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z))) r9: active(from(X)) -> mark(cons(X,from(s(X)))) r10: mark(and(X1,X2)) -> active(and(mark(X1),X2)) r11: mark(true()) -> active(true()) r12: mark(false()) -> active(false()) r13: mark(if(X1,X2,X3)) -> active(if(mark(X1),X2,X3)) r14: mark(add(X1,X2)) -> active(add(mark(X1),X2)) r15: mark(|0|()) -> active(|0|()) r16: mark(s(X)) -> active(s(X)) r17: mark(first(X1,X2)) -> active(first(mark(X1),mark(X2))) r18: mark(nil()) -> active(nil()) r19: mark(cons(X1,X2)) -> active(cons(X1,X2)) r20: mark(from(X)) -> active(from(X)) r21: and(mark(X1),X2) -> and(X1,X2) r22: and(X1,mark(X2)) -> and(X1,X2) r23: and(active(X1),X2) -> and(X1,X2) r24: and(X1,active(X2)) -> and(X1,X2) r25: if(mark(X1),X2,X3) -> if(X1,X2,X3) r26: if(X1,mark(X2),X3) -> if(X1,X2,X3) r27: if(X1,X2,mark(X3)) -> if(X1,X2,X3) r28: if(active(X1),X2,X3) -> if(X1,X2,X3) r29: if(X1,active(X2),X3) -> if(X1,X2,X3) r30: if(X1,X2,active(X3)) -> if(X1,X2,X3) r31: add(mark(X1),X2) -> add(X1,X2) r32: add(X1,mark(X2)) -> add(X1,X2) r33: add(active(X1),X2) -> add(X1,X2) r34: add(X1,active(X2)) -> add(X1,X2) r35: s(mark(X)) -> s(X) r36: s(active(X)) -> s(X) r37: first(mark(X1),X2) -> first(X1,X2) r38: first(X1,mark(X2)) -> first(X1,X2) r39: first(active(X1),X2) -> first(X1,X2) r40: first(X1,active(X2)) -> first(X1,X2) r41: cons(mark(X1),X2) -> cons(X1,X2) r42: cons(X1,mark(X2)) -> cons(X1,X2) r43: cons(active(X1),X2) -> cons(X1,X2) r44: cons(X1,active(X2)) -> cons(X1,X2) r45: from(mark(X)) -> from(X) r46: from(active(X)) -> from(X) The set of usable rules consists of (no rules) Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: add#_A(x1,x2) = max{2, x1 + 1, x2 + 1} mark_A(x1) = max{1, x1} active_A(x1) = max{1, x1} precedence: add# = mark = active partial status: pi(add#) = [1, 2] pi(mark) = [1] pi(active) = [1] 2. weighted path order base order: max/plus interpretations on natural numbers: add#_A(x1,x2) = max{x1 + 1, x2 - 1} mark_A(x1) = x1 active_A(x1) = x1 precedence: add# = mark = active partial status: pi(add#) = [1] pi(mark) = [1] pi(active) = [1] The next rules are strictly ordered: p1, p2, p3, p4 We remove them from the problem. Then no dependency pair remains. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: cons#(mark(X1),X2) -> cons#(X1,X2) p2: cons#(X1,active(X2)) -> cons#(X1,X2) p3: cons#(active(X1),X2) -> cons#(X1,X2) p4: cons#(X1,mark(X2)) -> cons#(X1,X2) and R consists of: r1: active(and(true(),X)) -> mark(X) r2: active(and(false(),Y)) -> mark(false()) r3: active(if(true(),X,Y)) -> mark(X) r4: active(if(false(),X,Y)) -> mark(Y) r5: active(add(|0|(),X)) -> mark(X) r6: active(add(s(X),Y)) -> mark(s(add(X,Y))) r7: active(first(|0|(),X)) -> mark(nil()) r8: active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z))) r9: active(from(X)) -> mark(cons(X,from(s(X)))) r10: mark(and(X1,X2)) -> active(and(mark(X1),X2)) r11: mark(true()) -> active(true()) r12: mark(false()) -> active(false()) r13: mark(if(X1,X2,X3)) -> active(if(mark(X1),X2,X3)) r14: mark(add(X1,X2)) -> active(add(mark(X1),X2)) r15: mark(|0|()) -> active(|0|()) r16: mark(s(X)) -> active(s(X)) r17: mark(first(X1,X2)) -> active(first(mark(X1),mark(X2))) r18: mark(nil()) -> active(nil()) r19: mark(cons(X1,X2)) -> active(cons(X1,X2)) r20: mark(from(X)) -> active(from(X)) r21: and(mark(X1),X2) -> and(X1,X2) r22: and(X1,mark(X2)) -> and(X1,X2) r23: and(active(X1),X2) -> and(X1,X2) r24: and(X1,active(X2)) -> and(X1,X2) r25: if(mark(X1),X2,X3) -> if(X1,X2,X3) r26: if(X1,mark(X2),X3) -> if(X1,X2,X3) r27: if(X1,X2,mark(X3)) -> if(X1,X2,X3) r28: if(active(X1),X2,X3) -> if(X1,X2,X3) r29: if(X1,active(X2),X3) -> if(X1,X2,X3) r30: if(X1,X2,active(X3)) -> if(X1,X2,X3) r31: add(mark(X1),X2) -> add(X1,X2) r32: add(X1,mark(X2)) -> add(X1,X2) r33: add(active(X1),X2) -> add(X1,X2) r34: add(X1,active(X2)) -> add(X1,X2) r35: s(mark(X)) -> s(X) r36: s(active(X)) -> s(X) r37: first(mark(X1),X2) -> first(X1,X2) r38: first(X1,mark(X2)) -> first(X1,X2) r39: first(active(X1),X2) -> first(X1,X2) r40: first(X1,active(X2)) -> first(X1,X2) r41: cons(mark(X1),X2) -> cons(X1,X2) r42: cons(X1,mark(X2)) -> cons(X1,X2) r43: cons(active(X1),X2) -> cons(X1,X2) r44: cons(X1,active(X2)) -> cons(X1,X2) r45: from(mark(X)) -> from(X) r46: from(active(X)) -> from(X) The set of usable rules consists of (no rules) Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: cons#_A(x1,x2) = max{2, x1 + 1, x2 + 1} mark_A(x1) = max{1, x1} active_A(x1) = max{1, x1} precedence: cons# = mark = active partial status: pi(cons#) = [1, 2] pi(mark) = [1] pi(active) = [1] 2. weighted path order base order: max/plus interpretations on natural numbers: cons#_A(x1,x2) = max{x1 + 1, x2 - 1} mark_A(x1) = x1 active_A(x1) = x1 precedence: cons# = mark = active partial status: pi(cons#) = [1] pi(mark) = [1] pi(active) = [1] The next rules are strictly ordered: p1, p2, p3, p4 We remove them from the problem. Then no dependency pair remains. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: first#(mark(X1),X2) -> first#(X1,X2) p2: first#(X1,active(X2)) -> first#(X1,X2) p3: first#(active(X1),X2) -> first#(X1,X2) p4: first#(X1,mark(X2)) -> first#(X1,X2) and R consists of: r1: active(and(true(),X)) -> mark(X) r2: active(and(false(),Y)) -> mark(false()) r3: active(if(true(),X,Y)) -> mark(X) r4: active(if(false(),X,Y)) -> mark(Y) r5: active(add(|0|(),X)) -> mark(X) r6: active(add(s(X),Y)) -> mark(s(add(X,Y))) r7: active(first(|0|(),X)) -> mark(nil()) r8: active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z))) r9: active(from(X)) -> mark(cons(X,from(s(X)))) r10: mark(and(X1,X2)) -> active(and(mark(X1),X2)) r11: mark(true()) -> active(true()) r12: mark(false()) -> active(false()) r13: mark(if(X1,X2,X3)) -> active(if(mark(X1),X2,X3)) r14: mark(add(X1,X2)) -> active(add(mark(X1),X2)) r15: mark(|0|()) -> active(|0|()) r16: mark(s(X)) -> active(s(X)) r17: mark(first(X1,X2)) -> active(first(mark(X1),mark(X2))) r18: mark(nil()) -> active(nil()) r19: mark(cons(X1,X2)) -> active(cons(X1,X2)) r20: mark(from(X)) -> active(from(X)) r21: and(mark(X1),X2) -> and(X1,X2) r22: and(X1,mark(X2)) -> and(X1,X2) r23: and(active(X1),X2) -> and(X1,X2) r24: and(X1,active(X2)) -> and(X1,X2) r25: if(mark(X1),X2,X3) -> if(X1,X2,X3) r26: if(X1,mark(X2),X3) -> if(X1,X2,X3) r27: if(X1,X2,mark(X3)) -> if(X1,X2,X3) r28: if(active(X1),X2,X3) -> if(X1,X2,X3) r29: if(X1,active(X2),X3) -> if(X1,X2,X3) r30: if(X1,X2,active(X3)) -> if(X1,X2,X3) r31: add(mark(X1),X2) -> add(X1,X2) r32: add(X1,mark(X2)) -> add(X1,X2) r33: add(active(X1),X2) -> add(X1,X2) r34: add(X1,active(X2)) -> add(X1,X2) r35: s(mark(X)) -> s(X) r36: s(active(X)) -> s(X) r37: first(mark(X1),X2) -> first(X1,X2) r38: first(X1,mark(X2)) -> first(X1,X2) r39: first(active(X1),X2) -> first(X1,X2) r40: first(X1,active(X2)) -> first(X1,X2) r41: cons(mark(X1),X2) -> cons(X1,X2) r42: cons(X1,mark(X2)) -> cons(X1,X2) r43: cons(active(X1),X2) -> cons(X1,X2) r44: cons(X1,active(X2)) -> cons(X1,X2) r45: from(mark(X)) -> from(X) r46: from(active(X)) -> from(X) The set of usable rules consists of (no rules) Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: first#_A(x1,x2) = max{2, x1 + 1, x2 + 1} mark_A(x1) = max{1, x1} active_A(x1) = max{1, x1} precedence: first# = mark = active partial status: pi(first#) = [1, 2] pi(mark) = [1] pi(active) = [1] 2. weighted path order base order: max/plus interpretations on natural numbers: first#_A(x1,x2) = max{x1 + 1, x2 - 1} mark_A(x1) = x1 active_A(x1) = x1 precedence: first# = mark = active partial status: pi(first#) = [1] pi(mark) = [1] pi(active) = [1] The next rules are strictly ordered: p1, p2, p3, p4 We remove them from the problem. Then no dependency pair remains. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: from#(mark(X)) -> from#(X) p2: from#(active(X)) -> from#(X) and R consists of: r1: active(and(true(),X)) -> mark(X) r2: active(and(false(),Y)) -> mark(false()) r3: active(if(true(),X,Y)) -> mark(X) r4: active(if(false(),X,Y)) -> mark(Y) r5: active(add(|0|(),X)) -> mark(X) r6: active(add(s(X),Y)) -> mark(s(add(X,Y))) r7: active(first(|0|(),X)) -> mark(nil()) r8: active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z))) r9: active(from(X)) -> mark(cons(X,from(s(X)))) r10: mark(and(X1,X2)) -> active(and(mark(X1),X2)) r11: mark(true()) -> active(true()) r12: mark(false()) -> active(false()) r13: mark(if(X1,X2,X3)) -> active(if(mark(X1),X2,X3)) r14: mark(add(X1,X2)) -> active(add(mark(X1),X2)) r15: mark(|0|()) -> active(|0|()) r16: mark(s(X)) -> active(s(X)) r17: mark(first(X1,X2)) -> active(first(mark(X1),mark(X2))) r18: mark(nil()) -> active(nil()) r19: mark(cons(X1,X2)) -> active(cons(X1,X2)) r20: mark(from(X)) -> active(from(X)) r21: and(mark(X1),X2) -> and(X1,X2) r22: and(X1,mark(X2)) -> and(X1,X2) r23: and(active(X1),X2) -> and(X1,X2) r24: and(X1,active(X2)) -> and(X1,X2) r25: if(mark(X1),X2,X3) -> if(X1,X2,X3) r26: if(X1,mark(X2),X3) -> if(X1,X2,X3) r27: if(X1,X2,mark(X3)) -> if(X1,X2,X3) r28: if(active(X1),X2,X3) -> if(X1,X2,X3) r29: if(X1,active(X2),X3) -> if(X1,X2,X3) r30: if(X1,X2,active(X3)) -> if(X1,X2,X3) r31: add(mark(X1),X2) -> add(X1,X2) r32: add(X1,mark(X2)) -> add(X1,X2) r33: add(active(X1),X2) -> add(X1,X2) r34: add(X1,active(X2)) -> add(X1,X2) r35: s(mark(X)) -> s(X) r36: s(active(X)) -> s(X) r37: first(mark(X1),X2) -> first(X1,X2) r38: first(X1,mark(X2)) -> first(X1,X2) r39: first(active(X1),X2) -> first(X1,X2) r40: first(X1,active(X2)) -> first(X1,X2) r41: cons(mark(X1),X2) -> cons(X1,X2) r42: cons(X1,mark(X2)) -> cons(X1,X2) r43: cons(active(X1),X2) -> cons(X1,X2) r44: cons(X1,active(X2)) -> cons(X1,X2) r45: from(mark(X)) -> from(X) r46: from(active(X)) -> from(X) The set of usable rules consists of (no rules) Take the monotone reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: from#_A(x1) = x1 + 2 mark_A(x1) = x1 active_A(x1) = x1 + 2 precedence: mark > active > from# partial status: pi(from#) = [1] pi(mark) = [1] pi(active) = [1] 2. weighted path order base order: max/plus interpretations on natural numbers: from#_A(x1) = x1 + 1 mark_A(x1) = x1 active_A(x1) = x1 precedence: from# = mark = active partial status: pi(from#) = [1] pi(mark) = [1] pi(active) = [1] The next rules are strictly ordered: p1, p2 We remove them from the problem. Then no dependency pair remains. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: and#(mark(X1),X2) -> and#(X1,X2) p2: and#(X1,active(X2)) -> and#(X1,X2) p3: and#(active(X1),X2) -> and#(X1,X2) p4: and#(X1,mark(X2)) -> and#(X1,X2) and R consists of: r1: active(and(true(),X)) -> mark(X) r2: active(and(false(),Y)) -> mark(false()) r3: active(if(true(),X,Y)) -> mark(X) r4: active(if(false(),X,Y)) -> mark(Y) r5: active(add(|0|(),X)) -> mark(X) r6: active(add(s(X),Y)) -> mark(s(add(X,Y))) r7: active(first(|0|(),X)) -> mark(nil()) r8: active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z))) r9: active(from(X)) -> mark(cons(X,from(s(X)))) r10: mark(and(X1,X2)) -> active(and(mark(X1),X2)) r11: mark(true()) -> active(true()) r12: mark(false()) -> active(false()) r13: mark(if(X1,X2,X3)) -> active(if(mark(X1),X2,X3)) r14: mark(add(X1,X2)) -> active(add(mark(X1),X2)) r15: mark(|0|()) -> active(|0|()) r16: mark(s(X)) -> active(s(X)) r17: mark(first(X1,X2)) -> active(first(mark(X1),mark(X2))) r18: mark(nil()) -> active(nil()) r19: mark(cons(X1,X2)) -> active(cons(X1,X2)) r20: mark(from(X)) -> active(from(X)) r21: and(mark(X1),X2) -> and(X1,X2) r22: and(X1,mark(X2)) -> and(X1,X2) r23: and(active(X1),X2) -> and(X1,X2) r24: and(X1,active(X2)) -> and(X1,X2) r25: if(mark(X1),X2,X3) -> if(X1,X2,X3) r26: if(X1,mark(X2),X3) -> if(X1,X2,X3) r27: if(X1,X2,mark(X3)) -> if(X1,X2,X3) r28: if(active(X1),X2,X3) -> if(X1,X2,X3) r29: if(X1,active(X2),X3) -> if(X1,X2,X3) r30: if(X1,X2,active(X3)) -> if(X1,X2,X3) r31: add(mark(X1),X2) -> add(X1,X2) r32: add(X1,mark(X2)) -> add(X1,X2) r33: add(active(X1),X2) -> add(X1,X2) r34: add(X1,active(X2)) -> add(X1,X2) r35: s(mark(X)) -> s(X) r36: s(active(X)) -> s(X) r37: first(mark(X1),X2) -> first(X1,X2) r38: first(X1,mark(X2)) -> first(X1,X2) r39: first(active(X1),X2) -> first(X1,X2) r40: first(X1,active(X2)) -> first(X1,X2) r41: cons(mark(X1),X2) -> cons(X1,X2) r42: cons(X1,mark(X2)) -> cons(X1,X2) r43: cons(active(X1),X2) -> cons(X1,X2) r44: cons(X1,active(X2)) -> cons(X1,X2) r45: from(mark(X)) -> from(X) r46: from(active(X)) -> from(X) The set of usable rules consists of (no rules) Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: and#_A(x1,x2) = max{2, x1 + 1, x2 + 1} mark_A(x1) = max{1, x1} active_A(x1) = max{1, x1} precedence: and# = mark = active partial status: pi(and#) = [1, 2] pi(mark) = [1] pi(active) = [1] 2. weighted path order base order: max/plus interpretations on natural numbers: and#_A(x1,x2) = max{x1 + 1, x2 - 1} mark_A(x1) = x1 active_A(x1) = x1 precedence: and# = mark = active partial status: pi(and#) = [1] pi(mark) = [1] pi(active) = [1] The next rules are strictly ordered: p1, p2, p3, p4 We remove them from the problem. Then no dependency pair remains. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: if#(mark(X1),X2,X3) -> if#(X1,X2,X3) p2: if#(X1,X2,active(X3)) -> if#(X1,X2,X3) p3: if#(X1,active(X2),X3) -> if#(X1,X2,X3) p4: if#(active(X1),X2,X3) -> if#(X1,X2,X3) p5: if#(X1,X2,mark(X3)) -> if#(X1,X2,X3) p6: if#(X1,mark(X2),X3) -> if#(X1,X2,X3) and R consists of: r1: active(and(true(),X)) -> mark(X) r2: active(and(false(),Y)) -> mark(false()) r3: active(if(true(),X,Y)) -> mark(X) r4: active(if(false(),X,Y)) -> mark(Y) r5: active(add(|0|(),X)) -> mark(X) r6: active(add(s(X),Y)) -> mark(s(add(X,Y))) r7: active(first(|0|(),X)) -> mark(nil()) r8: active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z))) r9: active(from(X)) -> mark(cons(X,from(s(X)))) r10: mark(and(X1,X2)) -> active(and(mark(X1),X2)) r11: mark(true()) -> active(true()) r12: mark(false()) -> active(false()) r13: mark(if(X1,X2,X3)) -> active(if(mark(X1),X2,X3)) r14: mark(add(X1,X2)) -> active(add(mark(X1),X2)) r15: mark(|0|()) -> active(|0|()) r16: mark(s(X)) -> active(s(X)) r17: mark(first(X1,X2)) -> active(first(mark(X1),mark(X2))) r18: mark(nil()) -> active(nil()) r19: mark(cons(X1,X2)) -> active(cons(X1,X2)) r20: mark(from(X)) -> active(from(X)) r21: and(mark(X1),X2) -> and(X1,X2) r22: and(X1,mark(X2)) -> and(X1,X2) r23: and(active(X1),X2) -> and(X1,X2) r24: and(X1,active(X2)) -> and(X1,X2) r25: if(mark(X1),X2,X3) -> if(X1,X2,X3) r26: if(X1,mark(X2),X3) -> if(X1,X2,X3) r27: if(X1,X2,mark(X3)) -> if(X1,X2,X3) r28: if(active(X1),X2,X3) -> if(X1,X2,X3) r29: if(X1,active(X2),X3) -> if(X1,X2,X3) r30: if(X1,X2,active(X3)) -> if(X1,X2,X3) r31: add(mark(X1),X2) -> add(X1,X2) r32: add(X1,mark(X2)) -> add(X1,X2) r33: add(active(X1),X2) -> add(X1,X2) r34: add(X1,active(X2)) -> add(X1,X2) r35: s(mark(X)) -> s(X) r36: s(active(X)) -> s(X) r37: first(mark(X1),X2) -> first(X1,X2) r38: first(X1,mark(X2)) -> first(X1,X2) r39: first(active(X1),X2) -> first(X1,X2) r40: first(X1,active(X2)) -> first(X1,X2) r41: cons(mark(X1),X2) -> cons(X1,X2) r42: cons(X1,mark(X2)) -> cons(X1,X2) r43: cons(active(X1),X2) -> cons(X1,X2) r44: cons(X1,active(X2)) -> cons(X1,X2) r45: from(mark(X)) -> from(X) r46: from(active(X)) -> from(X) The set of usable rules consists of (no rules) Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: if#_A(x1,x2,x3) = max{3, x1 + 1, x2 + 1, x3 + 1} mark_A(x1) = max{2, x1 + 1} active_A(x1) = max{1, x1} precedence: if# = mark = active partial status: pi(if#) = [1, 2] pi(mark) = [1] pi(active) = [1] 2. weighted path order base order: max/plus interpretations on natural numbers: if#_A(x1,x2,x3) = max{2, x1 + 1, x2 + 1} mark_A(x1) = max{1, x1} active_A(x1) = x1 + 1 precedence: if# = mark = active partial status: pi(if#) = [1, 2] pi(mark) = [1] pi(active) = [] The next rules are strictly ordered: p1, p3, p4, p6 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: if#(X1,X2,active(X3)) -> if#(X1,X2,X3) p2: if#(X1,X2,mark(X3)) -> if#(X1,X2,X3) and R consists of: r1: active(and(true(),X)) -> mark(X) r2: active(and(false(),Y)) -> mark(false()) r3: active(if(true(),X,Y)) -> mark(X) r4: active(if(false(),X,Y)) -> mark(Y) r5: active(add(|0|(),X)) -> mark(X) r6: active(add(s(X),Y)) -> mark(s(add(X,Y))) r7: active(first(|0|(),X)) -> mark(nil()) r8: active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z))) r9: active(from(X)) -> mark(cons(X,from(s(X)))) r10: mark(and(X1,X2)) -> active(and(mark(X1),X2)) r11: mark(true()) -> active(true()) r12: mark(false()) -> active(false()) r13: mark(if(X1,X2,X3)) -> active(if(mark(X1),X2,X3)) r14: mark(add(X1,X2)) -> active(add(mark(X1),X2)) r15: mark(|0|()) -> active(|0|()) r16: mark(s(X)) -> active(s(X)) r17: mark(first(X1,X2)) -> active(first(mark(X1),mark(X2))) r18: mark(nil()) -> active(nil()) r19: mark(cons(X1,X2)) -> active(cons(X1,X2)) r20: mark(from(X)) -> active(from(X)) r21: and(mark(X1),X2) -> and(X1,X2) r22: and(X1,mark(X2)) -> and(X1,X2) r23: and(active(X1),X2) -> and(X1,X2) r24: and(X1,active(X2)) -> and(X1,X2) r25: if(mark(X1),X2,X3) -> if(X1,X2,X3) r26: if(X1,mark(X2),X3) -> if(X1,X2,X3) r27: if(X1,X2,mark(X3)) -> if(X1,X2,X3) r28: if(active(X1),X2,X3) -> if(X1,X2,X3) r29: if(X1,active(X2),X3) -> if(X1,X2,X3) r30: if(X1,X2,active(X3)) -> if(X1,X2,X3) r31: add(mark(X1),X2) -> add(X1,X2) r32: add(X1,mark(X2)) -> add(X1,X2) r33: add(active(X1),X2) -> add(X1,X2) r34: add(X1,active(X2)) -> add(X1,X2) r35: s(mark(X)) -> s(X) r36: s(active(X)) -> s(X) r37: first(mark(X1),X2) -> first(X1,X2) r38: first(X1,mark(X2)) -> first(X1,X2) r39: first(active(X1),X2) -> first(X1,X2) r40: first(X1,active(X2)) -> first(X1,X2) r41: cons(mark(X1),X2) -> cons(X1,X2) r42: cons(X1,mark(X2)) -> cons(X1,X2) r43: cons(active(X1),X2) -> cons(X1,X2) r44: cons(X1,active(X2)) -> cons(X1,X2) r45: from(mark(X)) -> from(X) r46: from(active(X)) -> from(X) The estimated dependency graph contains the following SCCs: {p1, p2} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: if#(X1,X2,active(X3)) -> if#(X1,X2,X3) p2: if#(X1,X2,mark(X3)) -> if#(X1,X2,X3) and R consists of: r1: active(and(true(),X)) -> mark(X) r2: active(and(false(),Y)) -> mark(false()) r3: active(if(true(),X,Y)) -> mark(X) r4: active(if(false(),X,Y)) -> mark(Y) r5: active(add(|0|(),X)) -> mark(X) r6: active(add(s(X),Y)) -> mark(s(add(X,Y))) r7: active(first(|0|(),X)) -> mark(nil()) r8: active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z))) r9: active(from(X)) -> mark(cons(X,from(s(X)))) r10: mark(and(X1,X2)) -> active(and(mark(X1),X2)) r11: mark(true()) -> active(true()) r12: mark(false()) -> active(false()) r13: mark(if(X1,X2,X3)) -> active(if(mark(X1),X2,X3)) r14: mark(add(X1,X2)) -> active(add(mark(X1),X2)) r15: mark(|0|()) -> active(|0|()) r16: mark(s(X)) -> active(s(X)) r17: mark(first(X1,X2)) -> active(first(mark(X1),mark(X2))) r18: mark(nil()) -> active(nil()) r19: mark(cons(X1,X2)) -> active(cons(X1,X2)) r20: mark(from(X)) -> active(from(X)) r21: and(mark(X1),X2) -> and(X1,X2) r22: and(X1,mark(X2)) -> and(X1,X2) r23: and(active(X1),X2) -> and(X1,X2) r24: and(X1,active(X2)) -> and(X1,X2) r25: if(mark(X1),X2,X3) -> if(X1,X2,X3) r26: if(X1,mark(X2),X3) -> if(X1,X2,X3) r27: if(X1,X2,mark(X3)) -> if(X1,X2,X3) r28: if(active(X1),X2,X3) -> if(X1,X2,X3) r29: if(X1,active(X2),X3) -> if(X1,X2,X3) r30: if(X1,X2,active(X3)) -> if(X1,X2,X3) r31: add(mark(X1),X2) -> add(X1,X2) r32: add(X1,mark(X2)) -> add(X1,X2) r33: add(active(X1),X2) -> add(X1,X2) r34: add(X1,active(X2)) -> add(X1,X2) r35: s(mark(X)) -> s(X) r36: s(active(X)) -> s(X) r37: first(mark(X1),X2) -> first(X1,X2) r38: first(X1,mark(X2)) -> first(X1,X2) r39: first(active(X1),X2) -> first(X1,X2) r40: first(X1,active(X2)) -> first(X1,X2) r41: cons(mark(X1),X2) -> cons(X1,X2) r42: cons(X1,mark(X2)) -> cons(X1,X2) r43: cons(active(X1),X2) -> cons(X1,X2) r44: cons(X1,active(X2)) -> cons(X1,X2) r45: from(mark(X)) -> from(X) r46: from(active(X)) -> from(X) The set of usable rules consists of (no rules) Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: if#_A(x1,x2,x3) = max{2, x1, x2 + 1, x3 + 1} active_A(x1) = max{1, x1} mark_A(x1) = max{1, x1} precedence: if# = active = mark partial status: pi(if#) = [1, 3] pi(active) = [1] pi(mark) = [1] 2. weighted path order base order: max/plus interpretations on natural numbers: if#_A(x1,x2,x3) = max{0, x3 - 2} active_A(x1) = max{3, x1 + 1} mark_A(x1) = x1 precedence: if# = active = mark partial status: pi(if#) = [] pi(active) = [1] pi(mark) = [1] The next rules are strictly ordered: p1, p2 We remove them from the problem. Then no dependency pair remains.