Term Rewriting System R:
[X, Y, Z, X1, X2]
a2nd(cons(X, cons(Y, Z))) -> mark(Y)
a2nd(X) -> 2nd(X)
afrom(X) -> cons(mark(X), from(s(X)))
afrom(X) -> from(X)
mark(2nd(X)) -> a2nd(mark(X))
mark(from(X)) -> afrom(mark(X))
mark(cons(X1, X2)) -> cons(mark(X1), X2)
mark(s(X)) -> s(mark(X))

Termination of R to be shown.

`   R`
`     ↳Dependency Pair Analysis`

R contains the following Dependency Pairs:

A2ND(cons(X, cons(Y, Z))) -> MARK(Y)
AFROM(X) -> MARK(X)
MARK(2nd(X)) -> A2ND(mark(X))
MARK(2nd(X)) -> MARK(X)
MARK(from(X)) -> AFROM(mark(X))
MARK(from(X)) -> MARK(X)
MARK(cons(X1, X2)) -> MARK(X1)
MARK(s(X)) -> MARK(X)

Furthermore, R contains one SCC.

`   R`
`     ↳DPs`
`       →DP Problem 1`
`         ↳Remaining Obligation(s)`

The following remains to be proven:
Dependency Pairs:

MARK(s(X)) -> MARK(X)
MARK(cons(X1, X2)) -> MARK(X1)
MARK(from(X)) -> MARK(X)
AFROM(X) -> MARK(X)
MARK(from(X)) -> AFROM(mark(X))
MARK(2nd(X)) -> MARK(X)
MARK(2nd(X)) -> A2ND(mark(X))
A2ND(cons(X, cons(Y, Z))) -> MARK(Y)

Rules:

a2nd(cons(X, cons(Y, Z))) -> mark(Y)
a2nd(X) -> 2nd(X)
afrom(X) -> cons(mark(X), from(s(X)))
afrom(X) -> from(X)
mark(2nd(X)) -> a2nd(mark(X))
mark(from(X)) -> afrom(mark(X))
mark(cons(X1, X2)) -> cons(mark(X1), X2)
mark(s(X)) -> s(mark(X))

Termination of R could not be shown.
Duration:
0:37 minutes