#558 ⟨
a
,
b
|
aaba
=
aaaa
⟩
Up:
Monoids with two generators and one relation
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#557
⟨
a
,
b
|
aaab
=
aaaa
⟩
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#559
⟨
a
,
b
|
aaba
=
aaab
⟩
Quick links
Properties
Rewriting system
Properties
Presentation has sum-of-sides 8
Infinite non-cancellative non-commutative monoid
Not left cancellative, because left multiplication by
a
is not injective:
a
⋅
aba
=
a
4
and
a
⋅
a
3
=
a
4
, however
aba
≠
a
3
Not right cancellative, because right multiplication by
a
is not injective:
a
2
b
⋅
a
=
a
4
and
a
3
⋅
a
=
a
4
, however
a
2
b
≠
a
3
Enveloping group is isomorphic to ℤ
Rewriting system
Format:
Pretty
Plain
Word to reduce:
Tips:
Lowercase letters stand for generators.
Spaces are ignored.
Numbers repeat the previous letter, e.g.
b90
.
Reduction strategy:
Leftmost
Rightmost
Path to normal form:
1
1
Reduction order:
Left-to-right shortlex with
a
<
b
Certificate
: derivations of all rewriting rules from the defining relations.
#
Rule
Proof
1.
a
2
ba
⇒
a
4
[1]
# ab:aaba=aaaa ab aaba=aaaa