ack(0, y) → s(y)
ack(s(x), 0) → ack(x, s(0))
ack(s(x), s(y)) → ack(x, ack(s(x), y))
Renamed function symbols to avoid clashes with predefined symbol.
Runtime Complexity TRS:
The TRS R consists of the following rules:
ack'(0', y) → s'(y)
ack'(s'(x), 0') → ack'(x, s'(0'))
ack'(s'(x), s'(y)) → ack'(x, ack'(s'(x), y))
Infered types.
Rules:
ack'(0', y) → s'(y)
ack'(s'(x), 0') → ack'(x, s'(0'))
ack'(s'(x), s'(y)) → ack'(x, ack'(s'(x), y))
Types:
ack' :: 0':s' → 0':s' → 0':s'
0' :: 0':s'
s' :: 0':s' → 0':s'
_hole_0':s'1 :: 0':s'
_gen_0':s'2 :: Nat → 0':s'
Heuristically decided to analyse the following defined symbols:
ack'
Rules:
ack'(0', y) → s'(y)
ack'(s'(x), 0') → ack'(x, s'(0'))
ack'(s'(x), s'(y)) → ack'(x, ack'(s'(x), y))
Types:
ack' :: 0':s' → 0':s' → 0':s'
0' :: 0':s'
s' :: 0':s' → 0':s'
_hole_0':s'1 :: 0':s'
_gen_0':s'2 :: Nat → 0':s'
Generator Equations:
_gen_0':s'2(0) ⇔ 0'
_gen_0':s'2(+(x, 1)) ⇔ s'(_gen_0':s'2(x))
The following defined symbols remain to be analysed:
ack'
Proved the following rewrite lemma:
ack'(_gen_0':s'2(1), _gen_0':s'2(+(1, _n4))) → _*3, rt ∈ Ω(n4)
Induction Base:
ack'(_gen_0':s'2(1), _gen_0':s'2(+(1, 0)))
Induction Step:
ack'(_gen_0':s'2(1), _gen_0':s'2(+(1, +(_$n5, 1)))) →RΩ(1)
ack'(_gen_0':s'2(0), ack'(s'(_gen_0':s'2(0)), _gen_0':s'2(+(1, _$n5)))) →IH
ack'(_gen_0':s'2(0), _*3)
We have rt ∈ Ω(n) and sz ∈ O(n). Thus, we have ircR ∈ Ω(n).
Rules:
ack'(0', y) → s'(y)
ack'(s'(x), 0') → ack'(x, s'(0'))
ack'(s'(x), s'(y)) → ack'(x, ack'(s'(x), y))
Types:
ack' :: 0':s' → 0':s' → 0':s'
0' :: 0':s'
s' :: 0':s' → 0':s'
_hole_0':s'1 :: 0':s'
_gen_0':s'2 :: Nat → 0':s'
Lemmas:
ack'(_gen_0':s'2(1), _gen_0':s'2(+(1, _n4))) → _*3, rt ∈ Ω(n4)
Generator Equations:
_gen_0':s'2(0) ⇔ 0'
_gen_0':s'2(+(x, 1)) ⇔ s'(_gen_0':s'2(x))
No more defined symbols left to analyse.
The lowerbound Ω(n) was proven with the following lemma:
ack'(_gen_0':s'2(1), _gen_0':s'2(+(1, _n4))) → _*3, rt ∈ Ω(n4)