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:

f(a, a) → f(a, b)
f(a, b) → f(s(a), c)
f(s(X), c) → f(X, c)
f(c, c) → f(a, a)

Rewrite Strategy: FULL

(1) DecreasingLoopProof (EQUIVALENT transformation)

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

(2) BOUNDS(n^1, INF)

(3) RenamingProof (EQUIVALENT transformation)

Renamed function symbols to avoid clashes with predefined symbol.

(4) Obligation:

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

f(a, a) → f(a, b)
f(a, b) → f(s(a), c)
f(s(X), c) → f(X, c)
f(c, c) → f(a, a)

S is empty.
Rewrite Strategy: FULL

(5) TypeInferenceProof (BOTH BOUNDS(ID, ID) transformation)

Infered types.

(6) Obligation:

TRS:
Rules:
f(a, a) → f(a, b)
f(a, b) → f(s(a), c)
f(s(X), c) → f(X, c)
f(c, c) → f(a, a)

Types:
f :: a:b:s:c → a:b:s:c → f
a :: a:b:s:c
b :: a:b:s:c
s :: a:b:s:c → a:b:s:c
c :: a:b:s:c
hole_f1_0 :: f
hole_a:b:s:c2_0 :: a:b:s:c
gen_a:b:s:c3_0 :: Nat → a:b:s:c

(7) OrderProof (LOWER BOUND(ID) transformation)

Heuristically decided to analyse the following defined symbols:
f

(8) Obligation:

TRS:
Rules:
f(a, a) → f(a, b)
f(a, b) → f(s(a), c)
f(s(X), c) → f(X, c)
f(c, c) → f(a, a)

Types:
f :: a:b:s:c → a:b:s:c → f
a :: a:b:s:c
b :: a:b:s:c
s :: a:b:s:c → a:b:s:c
c :: a:b:s:c
hole_f1_0 :: f
hole_a:b:s:c2_0 :: a:b:s:c
gen_a:b:s:c3_0 :: Nat → a:b:s:c

Generator Equations:
gen_a:b:s:c3_0(0) ⇔ c
gen_a:b:s:c3_0(+(x, 1)) ⇔ s(gen_a:b:s:c3_0(x))

The following defined symbols remain to be analysed:
f

(9) NoRewriteLemmaProof (LOWER BOUND(ID) transformation)

Could not prove a rewrite lemma for the defined symbol f.

(10) Obligation:

TRS:
Rules:
f(a, a) → f(a, b)
f(a, b) → f(s(a), c)
f(s(X), c) → f(X, c)
f(c, c) → f(a, a)

Types:
f :: a:b:s:c → a:b:s:c → f
a :: a:b:s:c
b :: a:b:s:c
s :: a:b:s:c → a:b:s:c
c :: a:b:s:c
hole_f1_0 :: f
hole_a:b:s:c2_0 :: a:b:s:c
gen_a:b:s:c3_0 :: Nat → a:b:s:c

Generator Equations:
gen_a:b:s:c3_0(0) ⇔ c
gen_a:b:s:c3_0(+(x, 1)) ⇔ s(gen_a:b:s:c3_0(x))

No more defined symbols left to analyse.