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 when applying the reduction pair processor with usable rules to remove from the DP problem
   pairs:
   
   app#(app(flatwith, f), app(node, xs)) -> app#(app(flatwithsub, f), xs)
   app#(app(flatwithsub, f), app(app(cons, x), xs)) -> app#(app(flatwith, f), x)
   app#(app(flatwithsub, f), app(app(cons, x), xs)) -> app#(app(flatwithsub, f), xs)
   rules:
   
   app(app(append, nil), ys) -> ys
   app(app(append, app(app(cons, x), xs)), ys) -> app(app(cons, x), app(app(append, xs), ys))
   app(app(flatwith, f), app(leaf, x)) -> app(app(cons, app(f, x)), nil)
   app(app(flatwith, f), app(node, xs)) -> app(app(flatwithsub, f), xs)
   app(app(flatwithsub, f), nil) -> nil
   app(app(flatwithsub, f), app(app(cons, x), xs)) -> app(app(append, app(app(flatwith, f), x)), app(app(flatwithsub, f), xs))
   
    the pairs 
   app#(app(flatwith, f), app(node, xs)) -> app#(app(flatwithsub, f), xs)
   app#(app(flatwithsub, f), app(app(cons, x), xs)) -> app#(app(flatwith, f), x)
   app#(app(flatwithsub, f), app(app(cons, x), xs)) -> app#(app(flatwithsub, f), xs)
   
   could not apply the generic root reduction pair processor with the following
   SCNP-version with mu = MS and the level mapping defined by 
   pi(app#) = [(1,2),(2,1)]
   Argument Filter: 
   pi(app#/2) = []
   pi(app/2) = [2,1]
   pi(flatwith/0) = []
   pi(node/0) = []
   pi(flatwithsub/0) = []
   pi(cons/0) = []
   
   RPO with the following precedence
   precedence(app#[2]) = 0
   precedence(app[2]) = 1
   precedence(flatwith[0]) = 0
   precedence(node[0]) = 2
   precedence(flatwithsub[0]) = 0
   precedence(cons[0]) = 3
   
   precedence(_) = 0
   and the following status
   status(app#[2]) = lex
   status(app[2]) = lex
   status(flatwith[0]) = lex
   status(node[0]) = lex
   status(flatwithsub[0]) = lex
   status(cons[0]) = lex
   
   status(_) = lex
   
   problem when orienting DPs
   cannot orient pair app#(app(flatwith, f), app(node, xs)) -> app#(app(flatwithsub, f), xs) strictly:
   [(app(flatwith, f),2),(app(node, xs),1)] >mu [(app(flatwithsub, f),2),(xs,1)] could not be ensured