YES Confluence Proof

Confluence Proof

by csi

Input

The rewrite relation of the following TRS is considered.

a b
f(a) g(a)
f(b) g(b)

Proof

1 Redundant Rules Transformation

To prove that the TRS is (non-)confluent, we show (non-)confluence of the following modified system:

f(b) g(b)
f(a) g(a)
a b
f(a) g(b)

All redundant rules that were added or removed can be simulated in 2 steps .

1.1 Critical Pair Closing System

Confluence is proven using the following terminating critical-pair-closing-system R:

a b
f(b) g(b)

1.1.1 Rule Removal

Using the linear polynomial interpretation over the naturals
[b] = 0
[g(x1)] = 1 · x1 + 0
[a] = 0
[f(x1)] = 1 · x1 + 1
the rule
a b
remains.

1.1.1.1 Rule Removal

Using the linear polynomial interpretation over the naturals
[b] = 0
[a] = 1
all rules could be removed.

1.1.1.1.1 R is empty

There are no rules in the TRS. Hence, it is terminating.

Tool configuration

csi