ceta_eq: termination proof not accepted
1: error below switch to dependency pairs
1.1: error below the reduction pair processor
 1.1.1: error below the reduction pair processor
  1.1.1.1: error below the dependency graph 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 when applying the reduction pair processor with usable rules to remove from the DP problem
       pairs:
       
       mark#(first(X1, X2)) -> mark#(X1)
       mark#(first(X1, X2)) -> mark#(X2)
       rules:
       
       a__first(0, X) -> nil
       a__first(s(X), cons(Y, Z)) -> cons(mark(Y), first(X, Z))
       a__first(X1, X2) -> first(X1, X2)
       a__from(X) -> cons(mark(X), from(s(X)))
       a__from(X) -> from(X)
       mark(first(X1, X2)) -> a__first(mark(X1), mark(X2))
       mark(from(X)) -> a__from(mark(X))
       mark(0) -> 0
       mark(nil) -> nil
       mark(s(X)) -> s(mark(X))
       mark(cons(X1, X2)) -> cons(mark(X1), X2)
       
        the pairs 
       mark#(first(X1, X2)) -> mark#(X1)
       mark#(first(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(first(x_1, x_2)) = 1 + x_2 + x_1
       problem when orienting DPs
       cannot orient pair mark#(first(X1, X2)) -> mark#(X1) strictly:
       [(mark#(first(X1, X2)),0),(first(X1, X2),0)] >mu [(mark#(X1),0),(X1,0)] could not be ensured