YES
  TPA v.1.0

Result: TRS is terminating

Default interpretations for symbols are not printed. For polynomial interpretations
and semantic labelling over N\{0,1} defaults are 2 for constants, identity for unary
symbols and x+y-2 for binary symbols. For semantic labelling over {0,1} (booleans)
defaults are 0 for constants, identity for unary symbols and disjunction for binary symbols.

[1]  TRS loaded from input file:
(1) f(s(X),X) -> f(X,a(X))
(2) f(X,c(X)) -> f(s(X),X)
(3) f(X,X) -> c(X)

[2]  Eliminate dummy symbol <a>, to obtain the following TRS:
(1a) f(s(X),X) -> f(X,#0)
(1b) f(s(X),X) -> #1(X)
(2) f(X,c(X)) -> f(s(X),X)
(3) f(X,X) -> c(X)

[3]  Use following polynomial interpretation:
[f(x,y)] = x + y + 1
rest default

  Remove rules with left hand side strictly bigger than right hand side:
(1b), (3)

[4]  Use following polynomial interpretation:
[c(x)] = x + 1
rest default

  Remove rules with left hand side strictly bigger than right hand side:
(2)

[5]  Use following polynomial interpretation:
[s(x)] = x + 1
rest default

  Remove rules with left hand side strictly bigger than right hand side:
(1a)

[6]  Since there are no remaining rules, termination is proved!

../tpdb/TRS/Rubio/koen.trs, 0., Y
Couldn't open file <60>: 60: No such file or directory