Term Rewriting System R:

   [X, Y]
   from(X) -> cons(X, from(s(X)))
   length(nil) -> 0
   length(cons(X, Y)) -> s(length1(Y))
   length1(X) -> length(X)

Termination of R to be shown.


This program has no overlaps, so it is sufficient to show innermost termination. 


R contains the following Dependency Pairs: 


   FROM(X) -> FROM(s(X))
   LENGTH(cons(X, Y)) -> LENGTH1(Y)
   LENGTH1(X) -> LENGTH(X)

Furthermore, R contains two SCCs.


SCC1:

FROM(X) -> FROM(s(X))

Found an infinite P-chain over R:
P = FROM(X) -> FROM(s(X))
R = []
s = FROM(X) evaluates to t = FROM(s(X))
Thus, s starts an infinite reduction as s matches t.


Non-Termination of R could be shown.

Duration: 0.483 seconds.