ceta_eq: termination proof not accepted
1: error below switch to dependency pairs
1.1: error below the dependency graph processor
 1.1.1: error below the reduction pair processor
  1.1.1.1: error below the reduction pair processor
   1.1.1.1.1: error below the reduction pair processor
    1.1.1.1.1.1: error below the dependency graph processor
     1.1.1.1.1.1.1: error below the reduction pair processor
      1.1.1.1.1.1.1.1: error below the dependency graph processor
       1.1.1.1.1.1.1.1.1: error below the reduction pair processor
        1.1.1.1.1.1.1.1.1.1: error below the dependency graph processor
         1.1.1.1.1.1.1.1.1.1.1: error below the reduction pair processor
          1.1.1.1.1.1.1.1.1.1.1.1: error below the reduction pair processor
           1.1.1.1.1.1.1.1.1.1.1.1.1: error when applying the reduction pair processor with usable rules to remove from the DP problem
            pairs:
            
            mark#(fst(X1, X2)) -> mark#(X1)
            mark#(fst(X1, X2)) -> mark#(X2)
            rules:
            
            a__add(0, X) -> mark(X)
            a__add(s(X), Y) -> s(add(X, Y))
            a__add(X1, X2) -> add(X1, X2)
            a__from(X) -> cons(mark(X), from(s(X)))
            a__from(X) -> from(X)
            a__fst(0, Z) -> nil
            a__fst(s(X), cons(Y, Z)) -> cons(mark(Y), fst(X, Z))
            a__fst(X1, X2) -> fst(X1, X2)
            a__len(nil) -> 0
            a__len(cons(X, Z)) -> s(len(Z))
            a__len(X) -> len(X)
            mark(fst(X1, X2)) -> a__fst(mark(X1), mark(X2))
            mark(from(X)) -> a__from(mark(X))
            mark(add(X1, X2)) -> a__add(mark(X1), mark(X2))
            mark(len(X)) -> a__len(mark(X))
            mark(0) -> 0
            mark(s(X)) -> s(X)
            mark(nil) -> nil
            mark(cons(X1, X2)) -> cons(mark(X1), X2)
            
             the pairs 
            mark#(fst(X1, X2)) -> mark#(X1)
            mark#(fst(X1, X2)) -> mark#(X2)
            
            could not apply the generic root reduction pair processor with the following
            SCNP-version with mu = MS and the level mapping defined by 
            pi(mark#) = [(epsilon,0),(1,0)]
            polynomial interpretration over naturals with negative constants
            Pol(mark#(x_1)) = 1
            Pol(fst(x_1, x_2)) = 1 + x_2 + x_1
            problem when orienting DPs
            cannot orient pair mark#(fst(X1, X2)) -> mark#(X1) strictly:
            [(mark#(fst(X1, X2)),0),(fst(X1, X2),0)] >mu [(mark#(X1),0),(X1,0)] could not be ensured