YES Problem 1: (VAR v_NonEmpty:S X:S X1:S X2:S Y:S Z:S) (RULES activate(n__first(X1:S,X2:S)) -> first(activate(X1:S),activate(X2:S)) activate(n__from(X:S)) -> from(activate(X:S)) activate(n__s(X:S)) -> s(activate(X:S)) activate(X:S) -> X:S first(s(X:S),cons(Y:S,Z:S)) -> cons(Y:S,n__first(X:S,activate(Z:S))) first(0,Z:S) -> nil first(X1:S,X2:S) -> n__first(X1:S,X2:S) from(X:S) -> cons(X:S,n__from(n__s(X:S))) from(X:S) -> n__from(X:S) s(X:S) -> n__s(X:S) sel(s(X:S),cons(Y:S,Z:S)) -> sel(X:S,activate(Z:S)) sel(0,cons(X:S,Z:S)) -> X:S ) Problem 1: Dependency Pairs Processor: -> Pairs: ACTIVATE(n__first(X1:S,X2:S)) -> ACTIVATE(X1:S) ACTIVATE(n__first(X1:S,X2:S)) -> ACTIVATE(X2:S) ACTIVATE(n__first(X1:S,X2:S)) -> FIRST(activate(X1:S),activate(X2:S)) ACTIVATE(n__from(X:S)) -> ACTIVATE(X:S) ACTIVATE(n__from(X:S)) -> FROM(activate(X:S)) ACTIVATE(n__s(X:S)) -> ACTIVATE(X:S) ACTIVATE(n__s(X:S)) -> S(activate(X:S)) FIRST(s(X:S),cons(Y:S,Z:S)) -> ACTIVATE(Z:S) SEL(s(X:S),cons(Y:S,Z:S)) -> ACTIVATE(Z:S) SEL(s(X:S),cons(Y:S,Z:S)) -> SEL(X:S,activate(Z:S)) -> Rules: activate(n__first(X1:S,X2:S)) -> first(activate(X1:S),activate(X2:S)) activate(n__from(X:S)) -> from(activate(X:S)) activate(n__s(X:S)) -> s(activate(X:S)) activate(X:S) -> X:S first(s(X:S),cons(Y:S,Z:S)) -> cons(Y:S,n__first(X:S,activate(Z:S))) first(0,Z:S) -> nil first(X1:S,X2:S) -> n__first(X1:S,X2:S) from(X:S) -> cons(X:S,n__from(n__s(X:S))) from(X:S) -> n__from(X:S) s(X:S) -> n__s(X:S) sel(s(X:S),cons(Y:S,Z:S)) -> sel(X:S,activate(Z:S)) sel(0,cons(X:S,Z:S)) -> X:S Problem 1: SCC Processor: -> Pairs: ACTIVATE(n__first(X1:S,X2:S)) -> ACTIVATE(X1:S) ACTIVATE(n__first(X1:S,X2:S)) -> ACTIVATE(X2:S) ACTIVATE(n__first(X1:S,X2:S)) -> FIRST(activate(X1:S),activate(X2:S)) ACTIVATE(n__from(X:S)) -> ACTIVATE(X:S) ACTIVATE(n__from(X:S)) -> FROM(activate(X:S)) ACTIVATE(n__s(X:S)) -> ACTIVATE(X:S) ACTIVATE(n__s(X:S)) -> S(activate(X:S)) FIRST(s(X:S),cons(Y:S,Z:S)) -> ACTIVATE(Z:S) SEL(s(X:S),cons(Y:S,Z:S)) -> ACTIVATE(Z:S) SEL(s(X:S),cons(Y:S,Z:S)) -> SEL(X:S,activate(Z:S)) -> Rules: activate(n__first(X1:S,X2:S)) -> first(activate(X1:S),activate(X2:S)) activate(n__from(X:S)) -> from(activate(X:S)) activate(n__s(X:S)) -> s(activate(X:S)) activate(X:S) -> X:S first(s(X:S),cons(Y:S,Z:S)) -> cons(Y:S,n__first(X:S,activate(Z:S))) first(0,Z:S) -> nil first(X1:S,X2:S) -> n__first(X1:S,X2:S) from(X:S) -> cons(X:S,n__from(n__s(X:S))) from(X:S) -> n__from(X:S) s(X:S) -> n__s(X:S) sel(s(X:S),cons(Y:S,Z:S)) -> sel(X:S,activate(Z:S)) sel(0,cons(X:S,Z:S)) -> X:S ->Strongly Connected Components: ->->Cycle: ->->-> Pairs: ACTIVATE(n__first(X1:S,X2:S)) -> ACTIVATE(X1:S) ACTIVATE(n__first(X1:S,X2:S)) -> ACTIVATE(X2:S) ACTIVATE(n__first(X1:S,X2:S)) -> FIRST(activate(X1:S),activate(X2:S)) ACTIVATE(n__from(X:S)) -> ACTIVATE(X:S) ACTIVATE(n__s(X:S)) -> ACTIVATE(X:S) FIRST(s(X:S),cons(Y:S,Z:S)) -> ACTIVATE(Z:S) ->->-> Rules: activate(n__first(X1:S,X2:S)) -> first(activate(X1:S),activate(X2:S)) activate(n__from(X:S)) -> from(activate(X:S)) activate(n__s(X:S)) -> s(activate(X:S)) activate(X:S) -> X:S first(s(X:S),cons(Y:S,Z:S)) -> cons(Y:S,n__first(X:S,activate(Z:S))) first(0,Z:S) -> nil first(X1:S,X2:S) -> n__first(X1:S,X2:S) from(X:S) -> cons(X:S,n__from(n__s(X:S))) from(X:S) -> n__from(X:S) s(X:S) -> n__s(X:S) sel(s(X:S),cons(Y:S,Z:S)) -> sel(X:S,activate(Z:S)) sel(0,cons(X:S,Z:S)) -> X:S ->->Cycle: ->->-> Pairs: SEL(s(X:S),cons(Y:S,Z:S)) -> SEL(X:S,activate(Z:S)) ->->-> Rules: activate(n__first(X1:S,X2:S)) -> first(activate(X1:S),activate(X2:S)) activate(n__from(X:S)) -> from(activate(X:S)) activate(n__s(X:S)) -> s(activate(X:S)) activate(X:S) -> X:S first(s(X:S),cons(Y:S,Z:S)) -> cons(Y:S,n__first(X:S,activate(Z:S))) first(0,Z:S) -> nil first(X1:S,X2:S) -> n__first(X1:S,X2:S) from(X:S) -> cons(X:S,n__from(n__s(X:S))) from(X:S) -> n__from(X:S) s(X:S) -> n__s(X:S) sel(s(X:S),cons(Y:S,Z:S)) -> sel(X:S,activate(Z:S)) sel(0,cons(X:S,Z:S)) -> X:S The problem is decomposed in 2 subproblems. Problem 1.1: Reduction Pair Processor: -> Pairs: ACTIVATE(n__first(X1:S,X2:S)) -> ACTIVATE(X1:S) ACTIVATE(n__first(X1:S,X2:S)) -> ACTIVATE(X2:S) ACTIVATE(n__first(X1:S,X2:S)) -> FIRST(activate(X1:S),activate(X2:S)) ACTIVATE(n__from(X:S)) -> ACTIVATE(X:S) ACTIVATE(n__s(X:S)) -> ACTIVATE(X:S) FIRST(s(X:S),cons(Y:S,Z:S)) -> ACTIVATE(Z:S) -> Rules: activate(n__first(X1:S,X2:S)) -> first(activate(X1:S),activate(X2:S)) activate(n__from(X:S)) -> from(activate(X:S)) activate(n__s(X:S)) -> s(activate(X:S)) activate(X:S) -> X:S first(s(X:S),cons(Y:S,Z:S)) -> cons(Y:S,n__first(X:S,activate(Z:S))) first(0,Z:S) -> nil first(X1:S,X2:S) -> n__first(X1:S,X2:S) from(X:S) -> cons(X:S,n__from(n__s(X:S))) from(X:S) -> n__from(X:S) s(X:S) -> n__s(X:S) sel(s(X:S),cons(Y:S,Z:S)) -> sel(X:S,activate(Z:S)) sel(0,cons(X:S,Z:S)) -> X:S -> Usable rules: activate(n__first(X1:S,X2:S)) -> first(activate(X1:S),activate(X2:S)) activate(n__from(X:S)) -> from(activate(X:S)) activate(n__s(X:S)) -> s(activate(X:S)) activate(X:S) -> X:S first(s(X:S),cons(Y:S,Z:S)) -> cons(Y:S,n__first(X:S,activate(Z:S))) first(0,Z:S) -> nil first(X1:S,X2:S) -> n__first(X1:S,X2:S) from(X:S) -> cons(X:S,n__from(n__s(X:S))) from(X:S) -> n__from(X:S) s(X:S) -> n__s(X:S) ->Interpretation type: Linear ->Coefficients: Natural Numbers ->Dimension: 1 ->Bound: 2 ->Interpretation: [activate](X) = X [first](X1,X2) = 2.X1 + 2.X2 + 1 [from](X) = 2.X + 2 [s](X) = X [0] = 2 [cons](X1,X2) = X2 [n__first](X1,X2) = 2.X1 + 2.X2 + 1 [n__from](X) = 2.X + 2 [n__s](X) = X [nil] = 2 [ACTIVATE](X) = 2.X + 2 [FIRST](X1,X2) = 2.X1 + 2.X2 + 2 Problem 1.1: SCC Processor: -> Pairs: ACTIVATE(n__first(X1:S,X2:S)) -> ACTIVATE(X2:S) ACTIVATE(n__first(X1:S,X2:S)) -> FIRST(activate(X1:S),activate(X2:S)) ACTIVATE(n__from(X:S)) -> ACTIVATE(X:S) ACTIVATE(n__s(X:S)) -> ACTIVATE(X:S) FIRST(s(X:S),cons(Y:S,Z:S)) -> ACTIVATE(Z:S) -> Rules: activate(n__first(X1:S,X2:S)) -> first(activate(X1:S),activate(X2:S)) activate(n__from(X:S)) -> from(activate(X:S)) activate(n__s(X:S)) -> s(activate(X:S)) activate(X:S) -> X:S first(s(X:S),cons(Y:S,Z:S)) -> cons(Y:S,n__first(X:S,activate(Z:S))) first(0,Z:S) -> nil first(X1:S,X2:S) -> n__first(X1:S,X2:S) from(X:S) -> cons(X:S,n__from(n__s(X:S))) from(X:S) -> n__from(X:S) s(X:S) -> n__s(X:S) sel(s(X:S),cons(Y:S,Z:S)) -> sel(X:S,activate(Z:S)) sel(0,cons(X:S,Z:S)) -> X:S ->Strongly Connected Components: ->->Cycle: ->->-> Pairs: ACTIVATE(n__first(X1:S,X2:S)) -> ACTIVATE(X2:S) ACTIVATE(n__first(X1:S,X2:S)) -> FIRST(activate(X1:S),activate(X2:S)) ACTIVATE(n__from(X:S)) -> ACTIVATE(X:S) ACTIVATE(n__s(X:S)) -> ACTIVATE(X:S) FIRST(s(X:S),cons(Y:S,Z:S)) -> ACTIVATE(Z:S) ->->-> Rules: activate(n__first(X1:S,X2:S)) -> first(activate(X1:S),activate(X2:S)) activate(n__from(X:S)) -> from(activate(X:S)) activate(n__s(X:S)) -> s(activate(X:S)) activate(X:S) -> X:S first(s(X:S),cons(Y:S,Z:S)) -> cons(Y:S,n__first(X:S,activate(Z:S))) first(0,Z:S) -> nil first(X1:S,X2:S) -> n__first(X1:S,X2:S) from(X:S) -> cons(X:S,n__from(n__s(X:S))) from(X:S) -> n__from(X:S) s(X:S) -> n__s(X:S) sel(s(X:S),cons(Y:S,Z:S)) -> sel(X:S,activate(Z:S)) sel(0,cons(X:S,Z:S)) -> X:S Problem 1.1: Reduction Pair Processor: -> Pairs: ACTIVATE(n__first(X1:S,X2:S)) -> ACTIVATE(X2:S) ACTIVATE(n__first(X1:S,X2:S)) -> FIRST(activate(X1:S),activate(X2:S)) ACTIVATE(n__from(X:S)) -> ACTIVATE(X:S) ACTIVATE(n__s(X:S)) -> ACTIVATE(X:S) FIRST(s(X:S),cons(Y:S,Z:S)) -> ACTIVATE(Z:S) -> Rules: activate(n__first(X1:S,X2:S)) -> first(activate(X1:S),activate(X2:S)) activate(n__from(X:S)) -> from(activate(X:S)) activate(n__s(X:S)) -> s(activate(X:S)) activate(X:S) -> X:S first(s(X:S),cons(Y:S,Z:S)) -> cons(Y:S,n__first(X:S,activate(Z:S))) first(0,Z:S) -> nil first(X1:S,X2:S) -> n__first(X1:S,X2:S) from(X:S) -> cons(X:S,n__from(n__s(X:S))) from(X:S) -> n__from(X:S) s(X:S) -> n__s(X:S) sel(s(X:S),cons(Y:S,Z:S)) -> sel(X:S,activate(Z:S)) sel(0,cons(X:S,Z:S)) -> X:S -> Usable rules: activate(n__first(X1:S,X2:S)) -> first(activate(X1:S),activate(X2:S)) activate(n__from(X:S)) -> from(activate(X:S)) activate(n__s(X:S)) -> s(activate(X:S)) activate(X:S) -> X:S first(s(X:S),cons(Y:S,Z:S)) -> cons(Y:S,n__first(X:S,activate(Z:S))) first(0,Z:S) -> nil first(X1:S,X2:S) -> n__first(X1:S,X2:S) from(X:S) -> cons(X:S,n__from(n__s(X:S))) from(X:S) -> n__from(X:S) s(X:S) -> n__s(X:S) ->Interpretation type: Linear ->Coefficients: Natural Numbers ->Dimension: 1 ->Bound: 2 ->Interpretation: [activate](X) = X [first](X1,X2) = 2.X1 + 2.X2 + 2 [from](X) = 2.X + 1 [s](X) = X [0] = 2 [cons](X1,X2) = X2 [n__first](X1,X2) = 2.X1 + 2.X2 + 2 [n__from](X) = 2.X + 1 [n__s](X) = X [nil] = 1 [ACTIVATE](X) = 2.X + 2 [FIRST](X1,X2) = X1 + 2.X2 + 2 Problem 1.1: SCC Processor: -> Pairs: ACTIVATE(n__first(X1:S,X2:S)) -> FIRST(activate(X1:S),activate(X2:S)) ACTIVATE(n__from(X:S)) -> ACTIVATE(X:S) ACTIVATE(n__s(X:S)) -> ACTIVATE(X:S) FIRST(s(X:S),cons(Y:S,Z:S)) -> ACTIVATE(Z:S) -> Rules: activate(n__first(X1:S,X2:S)) -> first(activate(X1:S),activate(X2:S)) activate(n__from(X:S)) -> from(activate(X:S)) activate(n__s(X:S)) -> s(activate(X:S)) activate(X:S) -> X:S first(s(X:S),cons(Y:S,Z:S)) -> cons(Y:S,n__first(X:S,activate(Z:S))) first(0,Z:S) -> nil first(X1:S,X2:S) -> n__first(X1:S,X2:S) from(X:S) -> cons(X:S,n__from(n__s(X:S))) from(X:S) -> n__from(X:S) s(X:S) -> n__s(X:S) sel(s(X:S),cons(Y:S,Z:S)) -> sel(X:S,activate(Z:S)) sel(0,cons(X:S,Z:S)) -> X:S ->Strongly Connected Components: ->->Cycle: ->->-> Pairs: ACTIVATE(n__first(X1:S,X2:S)) -> FIRST(activate(X1:S),activate(X2:S)) ACTIVATE(n__from(X:S)) -> ACTIVATE(X:S) ACTIVATE(n__s(X:S)) -> ACTIVATE(X:S) FIRST(s(X:S),cons(Y:S,Z:S)) -> ACTIVATE(Z:S) ->->-> Rules: activate(n__first(X1:S,X2:S)) -> first(activate(X1:S),activate(X2:S)) activate(n__from(X:S)) -> from(activate(X:S)) activate(n__s(X:S)) -> s(activate(X:S)) activate(X:S) -> X:S first(s(X:S),cons(Y:S,Z:S)) -> cons(Y:S,n__first(X:S,activate(Z:S))) first(0,Z:S) -> nil first(X1:S,X2:S) -> n__first(X1:S,X2:S) from(X:S) -> cons(X:S,n__from(n__s(X:S))) from(X:S) -> n__from(X:S) s(X:S) -> n__s(X:S) sel(s(X:S),cons(Y:S,Z:S)) -> sel(X:S,activate(Z:S)) sel(0,cons(X:S,Z:S)) -> X:S Problem 1.1: Reduction Pair Processor: -> Pairs: ACTIVATE(n__first(X1:S,X2:S)) -> FIRST(activate(X1:S),activate(X2:S)) ACTIVATE(n__from(X:S)) -> ACTIVATE(X:S) ACTIVATE(n__s(X:S)) -> ACTIVATE(X:S) FIRST(s(X:S),cons(Y:S,Z:S)) -> ACTIVATE(Z:S) -> Rules: activate(n__first(X1:S,X2:S)) -> first(activate(X1:S),activate(X2:S)) activate(n__from(X:S)) -> from(activate(X:S)) activate(n__s(X:S)) -> s(activate(X:S)) activate(X:S) -> X:S first(s(X:S),cons(Y:S,Z:S)) -> cons(Y:S,n__first(X:S,activate(Z:S))) first(0,Z:S) -> nil first(X1:S,X2:S) -> n__first(X1:S,X2:S) from(X:S) -> cons(X:S,n__from(n__s(X:S))) from(X:S) -> n__from(X:S) s(X:S) -> n__s(X:S) sel(s(X:S),cons(Y:S,Z:S)) -> sel(X:S,activate(Z:S)) sel(0,cons(X:S,Z:S)) -> X:S -> Usable rules: activate(n__first(X1:S,X2:S)) -> first(activate(X1:S),activate(X2:S)) activate(n__from(X:S)) -> from(activate(X:S)) activate(n__s(X:S)) -> s(activate(X:S)) activate(X:S) -> X:S first(s(X:S),cons(Y:S,Z:S)) -> cons(Y:S,n__first(X:S,activate(Z:S))) first(0,Z:S) -> nil first(X1:S,X2:S) -> n__first(X1:S,X2:S) from(X:S) -> cons(X:S,n__from(n__s(X:S))) from(X:S) -> n__from(X:S) s(X:S) -> n__s(X:S) ->Interpretation type: Linear ->Coefficients: Natural Numbers ->Dimension: 1 ->Bound: 2 ->Interpretation: [activate](X) = X [first](X1,X2) = 2.X1 + 2.X2 + 2 [from](X) = 2.X + 2 [s](X) = X [0] = 0 [cons](X1,X2) = X2 [n__first](X1,X2) = 2.X1 + 2.X2 + 2 [n__from](X) = 2.X + 2 [n__s](X) = X [nil] = 1 [ACTIVATE](X) = 2.X + 2 [FIRST](X1,X2) = X1 + 2.X2 + 2 Problem 1.1: SCC Processor: -> Pairs: ACTIVATE(n__from(X:S)) -> ACTIVATE(X:S) ACTIVATE(n__s(X:S)) -> ACTIVATE(X:S) FIRST(s(X:S),cons(Y:S,Z:S)) -> ACTIVATE(Z:S) -> Rules: activate(n__first(X1:S,X2:S)) -> first(activate(X1:S),activate(X2:S)) activate(n__from(X:S)) -> from(activate(X:S)) activate(n__s(X:S)) -> s(activate(X:S)) activate(X:S) -> X:S first(s(X:S),cons(Y:S,Z:S)) -> cons(Y:S,n__first(X:S,activate(Z:S))) first(0,Z:S) -> nil first(X1:S,X2:S) -> n__first(X1:S,X2:S) from(X:S) -> cons(X:S,n__from(n__s(X:S))) from(X:S) -> n__from(X:S) s(X:S) -> n__s(X:S) sel(s(X:S),cons(Y:S,Z:S)) -> sel(X:S,activate(Z:S)) sel(0,cons(X:S,Z:S)) -> X:S ->Strongly Connected Components: ->->Cycle: ->->-> Pairs: ACTIVATE(n__from(X:S)) -> ACTIVATE(X:S) ACTIVATE(n__s(X:S)) -> ACTIVATE(X:S) ->->-> Rules: activate(n__first(X1:S,X2:S)) -> first(activate(X1:S),activate(X2:S)) activate(n__from(X:S)) -> from(activate(X:S)) activate(n__s(X:S)) -> s(activate(X:S)) activate(X:S) -> X:S first(s(X:S),cons(Y:S,Z:S)) -> cons(Y:S,n__first(X:S,activate(Z:S))) first(0,Z:S) -> nil first(X1:S,X2:S) -> n__first(X1:S,X2:S) from(X:S) -> cons(X:S,n__from(n__s(X:S))) from(X:S) -> n__from(X:S) s(X:S) -> n__s(X:S) sel(s(X:S),cons(Y:S,Z:S)) -> sel(X:S,activate(Z:S)) sel(0,cons(X:S,Z:S)) -> X:S Problem 1.1: Subterm Processor: -> Pairs: ACTIVATE(n__from(X:S)) -> ACTIVATE(X:S) ACTIVATE(n__s(X:S)) -> ACTIVATE(X:S) -> Rules: activate(n__first(X1:S,X2:S)) -> first(activate(X1:S),activate(X2:S)) activate(n__from(X:S)) -> from(activate(X:S)) activate(n__s(X:S)) -> s(activate(X:S)) activate(X:S) -> X:S first(s(X:S),cons(Y:S,Z:S)) -> cons(Y:S,n__first(X:S,activate(Z:S))) first(0,Z:S) -> nil first(X1:S,X2:S) -> n__first(X1:S,X2:S) from(X:S) -> cons(X:S,n__from(n__s(X:S))) from(X:S) -> n__from(X:S) s(X:S) -> n__s(X:S) sel(s(X:S),cons(Y:S,Z:S)) -> sel(X:S,activate(Z:S)) sel(0,cons(X:S,Z:S)) -> X:S ->Projection: pi(ACTIVATE) = 1 Problem 1.1: SCC Processor: -> Pairs: Empty -> Rules: activate(n__first(X1:S,X2:S)) -> first(activate(X1:S),activate(X2:S)) activate(n__from(X:S)) -> from(activate(X:S)) activate(n__s(X:S)) -> s(activate(X:S)) activate(X:S) -> X:S first(s(X:S),cons(Y:S,Z:S)) -> cons(Y:S,n__first(X:S,activate(Z:S))) first(0,Z:S) -> nil first(X1:S,X2:S) -> n__first(X1:S,X2:S) from(X:S) -> cons(X:S,n__from(n__s(X:S))) from(X:S) -> n__from(X:S) s(X:S) -> n__s(X:S) sel(s(X:S),cons(Y:S,Z:S)) -> sel(X:S,activate(Z:S)) sel(0,cons(X:S,Z:S)) -> X:S ->Strongly Connected Components: There is no strongly connected component The problem is finite. Problem 1.2: Subterm Processor: -> Pairs: SEL(s(X:S),cons(Y:S,Z:S)) -> SEL(X:S,activate(Z:S)) -> Rules: activate(n__first(X1:S,X2:S)) -> first(activate(X1:S),activate(X2:S)) activate(n__from(X:S)) -> from(activate(X:S)) activate(n__s(X:S)) -> s(activate(X:S)) activate(X:S) -> X:S first(s(X:S),cons(Y:S,Z:S)) -> cons(Y:S,n__first(X:S,activate(Z:S))) first(0,Z:S) -> nil first(X1:S,X2:S) -> n__first(X1:S,X2:S) from(X:S) -> cons(X:S,n__from(n__s(X:S))) from(X:S) -> n__from(X:S) s(X:S) -> n__s(X:S) sel(s(X:S),cons(Y:S,Z:S)) -> sel(X:S,activate(Z:S)) sel(0,cons(X:S,Z:S)) -> X:S ->Projection: pi(SEL) = 1 Problem 1.2: SCC Processor: -> Pairs: Empty -> Rules: activate(n__first(X1:S,X2:S)) -> first(activate(X1:S),activate(X2:S)) activate(n__from(X:S)) -> from(activate(X:S)) activate(n__s(X:S)) -> s(activate(X:S)) activate(X:S) -> X:S first(s(X:S),cons(Y:S,Z:S)) -> cons(Y:S,n__first(X:S,activate(Z:S))) first(0,Z:S) -> nil first(X1:S,X2:S) -> n__first(X1:S,X2:S) from(X:S) -> cons(X:S,n__from(n__s(X:S))) from(X:S) -> n__from(X:S) s(X:S) -> n__s(X:S) sel(s(X:S),cons(Y:S,Z:S)) -> sel(X:S,activate(Z:S)) sel(0,cons(X:S,Z:S)) -> X:S ->Strongly Connected Components: There is no strongly connected component The problem is finite.