The Runtime Complexity (full) of the given CpxTRS could be proven to be BOUNDS(n^1, INF).

(0) Obligation:

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

rev(a) → a
rev(b) → b
rev(++(x, y)) → ++(rev(y), rev(x))
rev(++(x, x)) → rev(x)

Rewrite Strategy: FULL

(1) DecreasingLoopProof (EQUIVALENT transformation)

The following loop(s) give(s) rise to the lower bound Ω(n¹):
The rewrite sequence
rev(++(x, y)) →⁺ ++(rev(y), rev(x))
gives rise to a decreasing loop by considering the right hand sides subterm at position [0].
The pumping substitution is [y / ++(x, y)].
The result substitution is [ ].

(2) BOUNDS(n^1, INF)