〈a, b | ba=ab, aaaa=ab〉

Properties

• Infinite commutative monoid
• Isomorphic to commutative presentation: 〈a, b | 4b=a+b〉
• Grothendieck group is ℤ

Completion parameters

• Reduction order: left-to-right a/b

Complete rewriting system

1. ba ⇒ a⁴
2. ab ⇒ a⁴

Right Cayley graph (truncated)