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

(0) Obligation:

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

average(s(x), y) → average(x, s(y))
average(x, s(s(s(y)))) → s(average(s(x), y))
average(0, 0) → 0
average(0, s(0)) → 0
average(0, s(s(0))) → s(0)

Rewrite Strategy: INNERMOST

(1) CpxTrsToCdtProof (BOTH BOUNDS(ID, ID) transformation)

Converted CpxTRS to CDT

(2) Obligation:

Complexity Dependency Tuples Problem
Rules:

average(s(z0), z1) → average(z0, s(z1))
average(z0, s(s(s(z1)))) → s(average(s(z0), z1))
average(0, 0) → 0
average(0, s(0)) → 0
average(0, s(s(0))) → s(0)

Tuples:

AVERAGE(s(z0), z1) → c(AVERAGE(z0, s(z1)))
AVERAGE(z0, s(s(s(z1)))) → c1(AVERAGE(s(z0), z1))

S tuples:

AVERAGE(s(z0), z1) → c(AVERAGE(z0, s(z1)))
AVERAGE(z0, s(s(s(z1)))) → c1(AVERAGE(s(z0), z1))

K tuples:none
Defined Rule Symbols:

average

Defined Pair Symbols:

AVERAGE

Compound Symbols:

c, c1

(3) CdtPolyRedPairProof (UPPER BOUND (ADD(O(n^1))) transformation)

Found a reduction pair which oriented the following tuples strictly. Hence they can be removed from S.

AVERAGE(s(z0), z1) → c(AVERAGE(z0, s(z1)))
AVERAGE(z0, s(s(s(z1)))) → c1(AVERAGE(s(z0), z1))

We considered the (Usable) Rules:none
And the Tuples:

AVERAGE(s(z0), z1) → c(AVERAGE(z0, s(z1)))
AVERAGE(z0, s(s(s(z1)))) → c1(AVERAGE(s(z0), z1))

The order we found is given by the following interpretation:
Polynomial interpretation :

POL(AVERAGE(x₁, x₂)) = [4]x₁ + [2]x₂   
POL(c(x₁)) = x₁   
POL(c1(x₁)) = x₁   
POL(s(x₁)) = [2] + x₁   

(4) Obligation:

Complexity Dependency Tuples Problem
Rules:

average(s(z0), z1) → average(z0, s(z1))
average(z0, s(s(s(z1)))) → s(average(s(z0), z1))
average(0, 0) → 0
average(0, s(0)) → 0
average(0, s(s(0))) → s(0)

Tuples:

AVERAGE(s(z0), z1) → c(AVERAGE(z0, s(z1)))
AVERAGE(z0, s(s(s(z1)))) → c1(AVERAGE(s(z0), z1))

S tuples:none
K tuples:

AVERAGE(s(z0), z1) → c(AVERAGE(z0, s(z1)))
AVERAGE(z0, s(s(s(z1)))) → c1(AVERAGE(s(z0), z1))

Defined Rule Symbols:

average

Defined Pair Symbols:

AVERAGE

Compound Symbols:

c, c1

(5) SIsEmptyProof (EQUIVALENT transformation)

The set S is empty

(6) BOUNDS(O(1), O(1))