NO Problem 1: (VAR v_NonEmpty:S X:S Y:S Z:S) (RULES U11(tt) -> tt U21(tt) -> U22(isList) U22(tt) -> tt U31(tt) -> tt U41(tt) -> U42(isNeList) U42(tt) -> tt U51(tt) -> U52(isList) U52(tt) -> tt U61(tt) -> tt U71(tt) -> U72(isPal) U72(tt) -> tt U81(tt) -> tt __(__(X:S,Y:S),Z:S) -> __(X:S,__(Y:S,Z:S)) __(nil,X:S) -> X:S __(X:S,nil) -> X:S isList -> U11(isNeList) isList -> U21(isList) isList -> tt isNeList -> U31(isQid) isNeList -> U41(isList) isNeList -> U51(isNeList) isNePal -> U61(isQid) isNePal -> U71(isQid) isPal -> U81(isNePal) isPal -> tt isQid -> tt ) Problem 1: Dependency Pairs Processor: -> Pairs: U21#(tt) -> U22#(isList) U21#(tt) -> ISLIST U41#(tt) -> U42#(isNeList) U41#(tt) -> ISNELIST U51#(tt) -> U52#(isList) U51#(tt) -> ISLIST U71#(tt) -> U72#(isPal) U71#(tt) -> ISPAL __#(__(X:S,Y:S),Z:S) -> __#(X:S,__(Y:S,Z:S)) __#(__(X:S,Y:S),Z:S) -> __#(Y:S,Z:S) ISLIST -> U11#(isNeList) ISLIST -> U21#(isList) ISLIST -> ISLIST ISLIST -> ISNELIST ISNELIST -> U31#(isQid) ISNELIST -> U41#(isList) ISNELIST -> U51#(isNeList) ISNELIST -> ISLIST ISNELIST -> ISNELIST ISNELIST -> ISQID ISNEPAL -> U61#(isQid) ISNEPAL -> U71#(isQid) ISNEPAL -> ISQID ISPAL -> U81#(isNePal) ISPAL -> ISNEPAL -> Rules: U11(tt) -> tt U21(tt) -> U22(isList) U22(tt) -> tt U31(tt) -> tt U41(tt) -> U42(isNeList) U42(tt) -> tt U51(tt) -> U52(isList) U52(tt) -> tt U61(tt) -> tt U71(tt) -> U72(isPal) U72(tt) -> tt U81(tt) -> tt __(__(X:S,Y:S),Z:S) -> __(X:S,__(Y:S,Z:S)) __(nil,X:S) -> X:S __(X:S,nil) -> X:S isList -> U11(isNeList) isList -> U21(isList) isList -> tt isNeList -> U31(isQid) isNeList -> U41(isList) isNeList -> U51(isNeList) isNePal -> U61(isQid) isNePal -> U71(isQid) isPal -> U81(isNePal) isPal -> tt isQid -> tt Problem 1: Infinite Processor: -> Pairs: U21#(tt) -> U22#(isList) U21#(tt) -> ISLIST U41#(tt) -> U42#(isNeList) U41#(tt) -> ISNELIST U51#(tt) -> U52#(isList) U51#(tt) -> ISLIST U71#(tt) -> U72#(isPal) U71#(tt) -> ISPAL __#(__(X:S,Y:S),Z:S) -> __#(X:S,__(Y:S,Z:S)) __#(__(X:S,Y:S),Z:S) -> __#(Y:S,Z:S) ISLIST -> U11#(isNeList) ISLIST -> U21#(isList) ISLIST -> ISLIST ISLIST -> ISNELIST ISNELIST -> U31#(isQid) ISNELIST -> U41#(isList) ISNELIST -> U51#(isNeList) ISNELIST -> ISLIST ISNELIST -> ISNELIST ISNELIST -> ISQID ISNEPAL -> U61#(isQid) ISNEPAL -> U71#(isQid) ISNEPAL -> ISQID ISPAL -> U81#(isNePal) ISPAL -> ISNEPAL -> Rules: U11(tt) -> tt U21(tt) -> U22(isList) U22(tt) -> tt U31(tt) -> tt U41(tt) -> U42(isNeList) U42(tt) -> tt U51(tt) -> U52(isList) U52(tt) -> tt U61(tt) -> tt U71(tt) -> U72(isPal) U72(tt) -> tt U81(tt) -> tt __(__(X:S,Y:S),Z:S) -> __(X:S,__(Y:S,Z:S)) __(nil,X:S) -> X:S __(X:S,nil) -> X:S isList -> U11(isNeList) isList -> U21(isList) isList -> tt isNeList -> U31(isQid) isNeList -> U41(isList) isNeList -> U51(isNeList) isNePal -> U61(isQid) isNePal -> U71(isQid) isPal -> U81(isNePal) isPal -> tt isQid -> tt -> Pairs in cycle: ISLIST -> ISLIST ISNELIST -> ISNELIST The problem is infinite.