ceta_eq: termination proof not accepted
1: error below switch to dependency pairs
1.1: error below the dependency graph processor
 1.1.2: error below the reduction pair processor
  1.1.2.1: error when applying the reduction pair processor with usable rules to remove from the DP problem
   pairs:
   
   f#(mark(X1), X2, X3) -> f#(X1, X2, X3)
   f#(X1, mark(X2), X3) -> f#(X1, X2, X3)
   f#(X1, X2, mark(X3)) -> f#(X1, X2, X3)
   f#(X1, active(X2), X3) -> f#(X1, X2, X3)
   f#(X1, X2, active(X3)) -> f#(X1, X2, X3)
   rules:
   
   active(f(a, X, X)) -> mark(f(X, b, b))
   active(b) -> mark(a)
   f(mark(X1), X2, X3) -> f(X1, X2, X3)
   f(X1, mark(X2), X3) -> f(X1, X2, X3)
   f(X1, X2, mark(X3)) -> f(X1, X2, X3)
   f(active(X1), X2, X3) -> f(X1, X2, X3)
   f(X1, active(X2), X3) -> f(X1, X2, X3)
   f(X1, X2, active(X3)) -> f(X1, X2, X3)
   mark(f(X1, X2, X3)) -> active(f(X1, mark(X2), X3))
   mark(a) -> active(a)
   mark(b) -> active(b)
   
    the pairs 
   f#(X1, active(X2), X3) -> f#(X1, X2, X3)
   f#(X1, X2, active(X3)) -> f#(X1, X2, X3)
   
   could not apply the generic root reduction pair processor with the following
   SCNP-version with mu = MS and the level mapping defined by 
   pi(f#) = [(2,2),(3,3)]
   polynomial interpretration over naturals with negative constants
   Pol(f#(x_1, x_2, x_3)) = 0
   Pol(mark(x_1)) = x_1
   Pol(active(x_1)) = 1 + x_1
   problem when orienting DPs
   cannot orient pair f#(X1, mark(X2), X3) -> f#(X1, X2, X3) weakly:
   [(mark(X2),2),(X3,3)] >=mu [(X2,2),(X3,3)] could not be ensured