(0) Obligation:

Runtime Complexity TRS:
The TRS R consists of the following rules:

f(x, y) → f(x, x)
f(s(x), y) → f(y, x)

Rewrite Strategy: FULL

(1) InfiniteLowerBoundProof (EQUIVALENT transformation)

The loop following loop proves infinite runtime complexity:
The rewrite sequence
f(x, y) →+ f(x, x)
gives rise to a decreasing loop by considering the right hand sides subterm at position [].
The pumping substitution is [ ].
The result substitution is [y / x].