YES We show the termination of the TRS R: app(app(mapbt(),f),app(leaf(),x)) -> app(leaf(),app(f,x)) app(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app(app(app(branch(),app(f,x)),app(app(mapbt(),f),l)),app(app(mapbt(),f),r)) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(mapbt(),f),app(leaf(),x)) -> app#(leaf(),app(f,x)) p2: app#(app(mapbt(),f),app(leaf(),x)) -> app#(f,x) p3: app#(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app#(app(app(branch(),app(f,x)),app(app(mapbt(),f),l)),app(app(mapbt(),f),r)) p4: app#(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app#(app(branch(),app(f,x)),app(app(mapbt(),f),l)) p5: app#(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app#(branch(),app(f,x)) p6: app#(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app#(f,x) p7: app#(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app#(app(mapbt(),f),l) p8: app#(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app#(app(mapbt(),f),r) and R consists of: r1: app(app(mapbt(),f),app(leaf(),x)) -> app(leaf(),app(f,x)) r2: app(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app(app(app(branch(),app(f,x)),app(app(mapbt(),f),l)),app(app(mapbt(),f),r)) The estimated dependency graph contains the following SCCs: {p2, p6, p7, p8} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(mapbt(),f),app(leaf(),x)) -> app#(f,x) p2: app#(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app#(app(mapbt(),f),r) p3: app#(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app#(app(mapbt(),f),l) p4: app#(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app#(f,x) and R consists of: r1: app(app(mapbt(),f),app(leaf(),x)) -> app(leaf(),app(f,x)) r2: app(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app(app(app(branch(),app(f,x)),app(app(mapbt(),f),l)),app(app(mapbt(),f),r)) The set of usable rules consists of (no rules) Take the reduction pair: max/plus interpretations on natural numbers: app#_A(x1,x2) = max{x1, x2 + 3} app_A(x1,x2) = max{x1 - 1, x2 + 2} mapbt_A = 6 leaf_A = 0 branch_A = 2 The next rules are strictly ordered: p1 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app#(app(mapbt(),f),r) p2: app#(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app#(app(mapbt(),f),l) p3: app#(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app#(f,x) and R consists of: r1: app(app(mapbt(),f),app(leaf(),x)) -> app(leaf(),app(f,x)) r2: app(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app(app(app(branch(),app(f,x)),app(app(mapbt(),f),l)),app(app(mapbt(),f),r)) The estimated dependency graph contains the following SCCs: {p1, p2, p3} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app#(app(mapbt(),f),r) p2: app#(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app#(f,x) p3: app#(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app#(app(mapbt(),f),l) and R consists of: r1: app(app(mapbt(),f),app(leaf(),x)) -> app(leaf(),app(f,x)) r2: app(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app(app(app(branch(),app(f,x)),app(app(mapbt(),f),l)),app(app(mapbt(),f),r)) The set of usable rules consists of (no rules) Take the reduction pair: max/plus interpretations on natural numbers: app#_A(x1,x2) = max{0, x1 - 2} app_A(x1,x2) = max{x1 - 2, x2 + 3} mapbt_A = 5 branch_A = 5 The next rules are strictly ordered: p2 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app#(app(mapbt(),f),r) p2: app#(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app#(app(mapbt(),f),l) and R consists of: r1: app(app(mapbt(),f),app(leaf(),x)) -> app(leaf(),app(f,x)) r2: app(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app(app(app(branch(),app(f,x)),app(app(mapbt(),f),l)),app(app(mapbt(),f),r)) The estimated dependency graph contains the following SCCs: {p1, p2} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app#(app(mapbt(),f),r) p2: app#(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app#(app(mapbt(),f),l) and R consists of: r1: app(app(mapbt(),f),app(leaf(),x)) -> app(leaf(),app(f,x)) r2: app(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app(app(app(branch(),app(f,x)),app(app(mapbt(),f),l)),app(app(mapbt(),f),r)) The set of usable rules consists of (no rules) Take the reduction pair: max/plus interpretations on natural numbers: app#_A(x1,x2) = x2 + 5 app_A(x1,x2) = max{x1 - 2, x2 + 2} mapbt_A = 1 branch_A = 2 The next rules are strictly ordered: p1 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app#(app(mapbt(),f),l) and R consists of: r1: app(app(mapbt(),f),app(leaf(),x)) -> app(leaf(),app(f,x)) r2: app(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app(app(app(branch(),app(f,x)),app(app(mapbt(),f),l)),app(app(mapbt(),f),r)) The estimated dependency graph contains the following SCCs: {p1} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app#(app(mapbt(),f),l) and R consists of: r1: app(app(mapbt(),f),app(leaf(),x)) -> app(leaf(),app(f,x)) r2: app(app(mapbt(),f),app(app(app(branch(),x),l),r)) -> app(app(app(branch(),app(f,x)),app(app(mapbt(),f),l)),app(app(mapbt(),f),r)) The set of usable rules consists of (no rules) Take the reduction pair: max/plus interpretations on natural numbers: app#_A(x1,x2) = x2 + 2 app_A(x1,x2) = max{x1, x2 + 3} mapbt_A = 0 branch_A = 1 The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.