YES Problem: b(c(x)) -> a(a(x)) c(b(x)) -> a(c(x)) a(b(x)) -> a(a(x)) b(b(x)) -> a(b(x)) b(c(x)) -> b(c(x)) c(a(x)) -> a(b(x)) a(c(x)) -> c(b(x)) b(a(x)) -> c(a(x)) Proof: Church Rosser Transformation Processor (critical pair closing system, Thm 2.4): strict: weak: b(c(x)) -> a(a(x)) c(b(x)) -> a(c(x)) a(b(x)) -> a(a(x)) b(b(x)) -> a(b(x)) b(c(x)) -> b(c(x)) c(a(x)) -> a(b(x)) a(c(x)) -> c(b(x)) b(a(x)) -> c(a(x)) original problem: a(c(x154)) -> c(b(x154)) b(c(x155)) -> a(a(x155)) b(b(x168)) -> a(b(x168)) c(a(x170)) -> a(b(x170)) a(b(x172)) -> a(a(x172)) b(a(x175)) -> c(a(x175)) c(b(x189)) -> a(c(x189)) critical peaks: Shift Processor (no label): a(c(x154)) -> c(b(x154)) b(c(x155)) -> a(a(x155)) b(b(x168)) -> a(b(x168)) c(a(x170)) -> a(b(x170)) a(b(x172)) -> a(a(x172)) b(a(x175)) -> c(a(x175)) c(b(x189)) -> a(c(x189)) AT confluence processor Complete TRS T' of input TRS: b(c(x155)) -> a(a(x155)) b(b(x168)) -> a(b(x168)) c(a(x170)) -> a(b(x170)) a(b(x172)) -> a(a(x172)) b(a(x175)) -> c(a(x175)) c(c(b(x517))) -> a(a(a(x517))) a(c(c(x628))) -> a(a(a(x628))) a(c(b(x630))) -> a(a(a(x630))) a(a(c(x630))) -> a(a(a(x630))) a(c(x154)) -> c(b(x154)) c(b(x189)) -> a(c(x189)) T' = (P union S) with TRS P:a(c(x154)) -> c(b(x154)) c(b(x189)) -> a(c(x189)) TRS S:b(c(x155)) -> a(a(x155)) b(b(x168)) -> a(b(x168)) c(a(x170)) -> a(b(x170)) a(b(x172)) -> a(a(x172)) b(a(x175)) -> c(a(x175)) c(c(b(x517))) -> a(a(a(x517))) a(c(c(x628))) -> a(a(a(x628))) a(c(b(x630))) -> a(a(a(x630))) a(a(c(x630))) -> a(a(a(x630))) S is linear and P is reversible. CP(S,S) = b(a(a(x1348))) = a(b(c(x1348))), a(a(a(x1349))) = a(a(c(x1349))), c(c(a(a(x1350)))) = a(a(a(c(x1350)))), a(c(a(a(x1351)))) = a(a(a(c(x1351)))), b(a(b(x1352))) = a(b(b(x1352))), a(a(b(x1353))) = a(a(b(x1353))), c(c(a(b(x1354)))) = a(a(a(b(x1354)))), a(c(a(b(x1355)))) = a(a(a(b(x1355)))), b(a(b(x1356))) = a(a(a(x1356))), a(c(a(b(x1357)))) = a(a(a(a(x1357)))), a(a(a(b(x1358)))) = a(a(a(a(x1358)))), c(a(a(x1359))) = a(b(b(x1359))), b(a(a(x1360))) = c(a(b(x1360))), b(c(a(x1361))) = a(b(a(x1361))), a(c(a(x1362))) = a(a(a(x1362))), c(c(c(a(x1363)))) = a(a(a(a(x1363)))), a(c(c(a(x1364)))) = a(a(a(a(x1364)))), b(a(a(a(x1365)))) = a(a(c(b(x1365)))), a(a(a(a(x1366)))) = a(a(a(b(x1366)))), a(c(a(a(a(x1367))))) = a(a(a(c(b(x1367))))), a(a(a(a(a(x1368))))) = a(a(a(c(b(x1368))))), c(a(a(a(x1369)))) = a(b(c(c(x1369)))), b(a(a(a(x1370)))) = c(a(c(c(x1370)))), a(a(a(a(x1371)))) = a(a(a(c(x1371)))), c(a(a(a(x1372)))) = a(b(c(b(x1372)))), b(a(a(a(x1373)))) = c(a(c(b(x1373)))), a(a(a(a(x1374)))) = a(a(a(b(x1374)))), c(a(a(a(x1375)))) = a(b(a(c(x1375)))), b(a(a(a(x1376)))) = c(a(a(c(x1376)))) CP(S,P union P^-1) = c(a(a(x1449))) = a(c(c(x1449))), c(a(a(x1450))) = a(c(c(x1450))), c(a(b(x1451))) = a(c(b(x1451))), c(a(b(x1452))) = a(c(b(x1452))), a(a(b(x1453))) = c(b(a(x1453))), a(a(b(x1454))) = c(b(a(x1454))), c(c(a(x1455))) = a(c(a(x1455))), c(c(a(x1456))) = a(c(a(x1456))), a(a(a(a(x1457)))) = c(b(c(b(x1457)))), a(a(a(a(x1458)))) = c(b(c(b(x1458)))), a(a(a(x1459))) = c(b(c(x1459))), a(a(a(x1460))) = c(b(c(x1460))), a(a(a(x1461))) = c(b(b(x1461))), a(a(a(x1462))) = c(b(b(x1462))) CP(P union P^-1,S) = c(c(b(x1551))) = a(b(c(x1551))), b(c(b(x1552))) = c(a(c(x1552))), c(b(c(x628))) = a(a(a(x628))), c(b(b(x630))) = a(a(a(x630))), a(c(b(x630))) = a(a(a(x630))), b(a(c(x1556))) = a(a(b(x1556))), c(a(c(x517))) = a(a(a(x517))), a(c(a(c(x1558)))) = a(a(a(b(x1558)))), a(a(c(x630))) = a(a(a(x630))), a(a(a(c(x1560)))) = a(a(a(b(x1560)))), b(a(c(x1561))) = a(a(b(x1561))), a(c(a(c(x1563)))) = a(a(a(b(x1563)))), a(a(a(c(x1565)))) = a(a(a(b(x1565)))), c(c(b(x1566))) = a(b(c(x1566))), b(c(b(x1567))) = c(a(c(x1567))) We have to check termination of S: KBO Processor: weight function: w0 = 1 w(a) = w(b) = w(c) = 1 precedence: b > c > a problem: Qed