Consider the TRS R consisting of the rewrite rules 1: le(0,y) -> true 2: le(s(x),0) -> false 3: le(s(x),s(y)) -> le(x,y) 4: minus(0,y) -> 0 5: minus(s(x),y) -> if_minus(le(s(x),y),s(x),y) 6: if_minus(true,s(x),y) -> 0 7: if_minus(false,s(x),y) -> s(minus(x,y)) 8: quot(0,s(y)) -> 0 9: quot(s(x),s(y)) -> s(quot(minus(x,y),s(y))) 10: log(s(0)) -> 0 11: log(s(s(x))) -> s(log(s(quot(x,s(s(0)))))) There are 8 dependency pairs: 12: LE(s(x),s(y)) -> LE(x,y) 13: MINUS(s(x),y) -> IF_MINUS(le(s(x),y),s(x),y) 14: MINUS(s(x),y) -> LE(s(x),y) 15: IF_MINUS(false,s(x),y) -> MINUS(x,y) 16: QUOT(s(x),s(y)) -> QUOT(minus(x,y),s(y)) 17: QUOT(s(x),s(y)) -> MINUS(x,y) 18: LOG(s(s(x))) -> LOG(s(quot(x,s(s(0))))) 19: LOG(s(s(x))) -> QUOT(x,s(s(0))) The approximated dependency graph contains 4 SCCs: {12}, {13,15}, {16} and {18}. - Consider the SCC {12}. There are no usable rules. By taking the polynomial interpretation [s](x) = x + 1 and [LE](x,y) = x + y + 1, rule 12 is strictly decreasing. - Consider the SCC {13,15}. The usable rules are {1-3}. By taking the polynomial interpretation [0] = [false] = [true] = 1, [s](x) = x + 1, [le](x,y) = [MINUS](x,y) = x + y + 1 and [IF_MINUS](x,y,z) = y + z + 1, rule 13 is weakly decreasing and the rules in {1-3,15} are strictly decreasing. - Consider the SCC {16}. The usable rules are {1-7}. By taking the polynomial interpretation [0] = [false] = [true] = 1, [minus](x,y) = x, [s](x) = x + 1, [le](x,y) = [QUOT](x,y) = x + y + 1 and [if_minus](x,y,z) = y, the rules in {4-7} are weakly decreasing and the rules in {1-3,16} are strictly decreasing. - Consider the SCC {18}. The usable rules are {1-9}. By taking the polynomial interpretation [0] = [false] = [true] = 1, [minus](x,y) = [quot](x,y) = x, [LOG](x) = [s](x) = x + 1, [le](x,y) = x + y + 1 and [if_minus](x,y,z) = y, the rules in {4-9} are weakly decreasing and the rules in {1-3,18} are strictly decreasing. Hence the TRS is terminating.