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:

a__zeros → cons(0, zeros)
a__tail(cons(X, XS)) → mark(XS)
mark(zeros) → a__zeros
mark(tail(X)) → a__tail(mark(X))
mark(cons(X1, X2)) → cons(mark(X1), X2)
mark(0) → 0
a__zeros → zeros
a__tail(X) → tail(X)

Rewrite Strategy: FULL

(1) DecreasingLoopProof (EQUIVALENT transformation)

The following loop(s) give(s) rise to the lower bound Ω(n¹):
The rewrite sequence
a__tail(cons(X, tail(cons(X134_3, X235_3)))) →⁺ a__tail(cons(mark(X134_3), X235_3))
gives rise to a decreasing loop by considering the right hand sides subterm at position [].
The pumping substitution is [X235_3 / tail(cons(X134_3, X235_3))].
The result substitution is [X / mark(X134_3)].

(2) BOUNDS(n^1, INF)