#264 ⟨
a
,
b
|
abba
=
aab
⟩
Up:
Monoids with two generators and one relation
Prev:
#263
⟨
a
,
b
|
abba
=
aaa
⟩
Next:
#265
⟨
a
,
b
|
abba
=
aba
⟩
Quick links
Properties
Rewriting system
Properties
Presentation has sum-of-sides 7
Infinite non-cancellative non-commutative monoid
Not left cancellative, because left multiplication by
a
is not injective:
a
⋅
b
2
a
=
a
2
b
and
a
⋅
ab
=
a
2
b
, however
b
2
a
≠
ab
Enveloping group: ⟨
a
,
b
|
aaba
-1
b
-1
⟩
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:
Right-to-left recursive path with deg(
b
) = 0; deg(
a
) = 1
Certificate
: derivations of all rewriting rules from the defining relations.
#
Rule
Proof
1.
a
2
b
⇒
a
b
2
a
[1]
# ab:abba=aab reversed:b/a aab=abba