The Runtime Complexity (innermost) 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:

append(Cons(x, xs), ys) → Cons(x, append(xs, ys))
append(Nil, ys) → ys
goal(x, y) → append(x, y)

Rewrite Strategy: INNERMOST

(1) RenamingProof (EQUIVALENT transformation)

Renamed function symbols to avoid clashes with predefined symbol.

(2) Obligation:

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

append(Cons(x, xs), ys) → Cons(x, append(xs, ys))
append(Nil, ys) → ys
goal(x, y) → append(x, y)

S is empty.
Rewrite Strategy: INNERMOST

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

Infered types.

(4) Obligation:

Innermost TRS:
Rules:
append(Cons(x, xs), ys) → Cons(x, append(xs, ys))
append(Nil, ys) → ys
goal(x, y) → append(x, y)

Types:
append :: Cons:Nil → Cons:Nil → Cons:Nil
Cons :: a → Cons:Nil → Cons:Nil
Nil :: Cons:Nil
goal :: Cons:Nil → Cons:Nil → Cons:Nil
hole_Cons:Nil1_0 :: Cons:Nil
hole_a2_0 :: a
gen_Cons:Nil3_0 :: Nat → Cons:Nil

(5) OrderProof (LOWER BOUND(ID) transformation)

Heuristically decided to analyse the following defined symbols:
append

(6) Obligation:

Innermost TRS:
Rules:
append(Cons(x, xs), ys) → Cons(x, append(xs, ys))
append(Nil, ys) → ys
goal(x, y) → append(x, y)

Types:
append :: Cons:Nil → Cons:Nil → Cons:Nil
Cons :: a → Cons:Nil → Cons:Nil
Nil :: Cons:Nil
goal :: Cons:Nil → Cons:Nil → Cons:Nil
hole_Cons:Nil1_0 :: Cons:Nil
hole_a2_0 :: a
gen_Cons:Nil3_0 :: Nat → Cons:Nil

Generator Equations:
gen_Cons:Nil3_0(0) ⇔ Nil
gen_Cons:Nil3_0(+(x, 1)) ⇔ Cons(hole_a2_0, gen_Cons:Nil3_0(x))

The following defined symbols remain to be analysed:
append

(7) RewriteLemmaProof (LOWER BOUND(ID) transformation)

Proved the following rewrite lemma:
append(gen_Cons:Nil3_0(n5_0), gen_Cons:Nil3_0(b)) → gen_Cons:Nil3_0(+(n5_0, b)), rt ∈ Ω(1 + n5₀)

Induction Base:
append(gen_Cons:Nil3_0(0), gen_Cons:Nil3_0(b)) →_R^Ω(1)
gen_Cons:Nil3_0(b)

Induction Step:
append(gen_Cons:Nil3_0(+(n5_0, 1)), gen_Cons:Nil3_0(b)) →_R^Ω(1)
Cons(hole_a2_0, append(gen_Cons:Nil3_0(n5_0), gen_Cons:Nil3_0(b))) →_IH
Cons(hole_a2_0, gen_Cons:Nil3_0(+(b, c6_0)))

We have rt ∈ Ω(n¹) and sz ∈ O(n). Thus, we have irc_R ∈ Ω(n).

(8) Complex Obligation (BEST)

(9) Obligation:

Innermost TRS:
Rules:
append(Cons(x, xs), ys) → Cons(x, append(xs, ys))
append(Nil, ys) → ys
goal(x, y) → append(x, y)

Types:
append :: Cons:Nil → Cons:Nil → Cons:Nil
Cons :: a → Cons:Nil → Cons:Nil
Nil :: Cons:Nil
goal :: Cons:Nil → Cons:Nil → Cons:Nil
hole_Cons:Nil1_0 :: Cons:Nil
hole_a2_0 :: a
gen_Cons:Nil3_0 :: Nat → Cons:Nil

Lemmas:
append(gen_Cons:Nil3_0(n5_0), gen_Cons:Nil3_0(b)) → gen_Cons:Nil3_0(+(n5_0, b)), rt ∈ Ω(1 + n5₀)

Generator Equations:
gen_Cons:Nil3_0(0) ⇔ Nil
gen_Cons:Nil3_0(+(x, 1)) ⇔ Cons(hole_a2_0, gen_Cons:Nil3_0(x))

No more defined symbols left to analyse.

(10) LowerBoundsProof (EQUIVALENT transformation)

The lowerbound Ω(n¹) was proven with the following lemma:
append(gen_Cons:Nil3_0(n5_0), gen_Cons:Nil3_0(b)) → gen_Cons:Nil3_0(+(n5_0, b)), rt ∈ Ω(1 + n5₀)

(11) BOUNDS(n^1, INF)

(12) Obligation:

Innermost TRS:
Rules:
append(Cons(x, xs), ys) → Cons(x, append(xs, ys))
append(Nil, ys) → ys
goal(x, y) → append(x, y)

Types:
append :: Cons:Nil → Cons:Nil → Cons:Nil
Cons :: a → Cons:Nil → Cons:Nil
Nil :: Cons:Nil
goal :: Cons:Nil → Cons:Nil → Cons:Nil
hole_Cons:Nil1_0 :: Cons:Nil
hole_a2_0 :: a
gen_Cons:Nil3_0 :: Nat → Cons:Nil

Lemmas:
append(gen_Cons:Nil3_0(n5_0), gen_Cons:Nil3_0(b)) → gen_Cons:Nil3_0(+(n5_0, b)), rt ∈ Ω(1 + n5₀)

Generator Equations:
gen_Cons:Nil3_0(0) ⇔ Nil
gen_Cons:Nil3_0(+(x, 1)) ⇔ Cons(hole_a2_0, gen_Cons:Nil3_0(x))

No more defined symbols left to analyse.

(13) LowerBoundsProof (EQUIVALENT transformation)

The lowerbound Ω(n¹) was proven with the following lemma:
append(gen_Cons:Nil3_0(n5_0), gen_Cons:Nil3_0(b)) → gen_Cons:Nil3_0(+(n5_0, b)), rt ∈ Ω(1 + n5₀)

(14) BOUNDS(n^1, INF)