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-4 votes
1 answer
79 views

Practical example of differences between associativity and alternativity (and the in-between Bol loop)? [closed]

Associativity is: $$(a * b) * c = a * (b * c)$$ Alternativity is: $$a * (a * b) = (a * a) * b$$ $$(a * b) * b = a * (b * b)$$ Bol loop is: $${\displaystyle a(b(ac))=(a(ba))c}$$ $${\displaystyle ((ca)b)...
Lance's user avatar
  • 3,773
0 votes
1 answer
55 views

Term for a Set Equipped With a Binary Operation Which Contains Inverses

Let $A$ be a set and let $\circ:A\times A\rightarrow B,$ $A\subseteq B$ be a binary operation ($A$ is not necessarily closed under $\circ$). If there exists some unique $e\in A$ such that $e\circ a=a\...
Miles Gould's user avatar
5 votes
1 answer
160 views

Do the Moufang identities *themselves* imply diassociativity / Moufang's theorem / Artin's theorem?

A Moufang loop is a loop satisfying the Moufang identities. Famously, these are diassociative -- the subloop generated by any two elements is associative (is a group) -- and more generally, they ...
Harry Altman's user avatar
  • 4,742
1 vote
1 answer
233 views

Inverse element of a magma

It is accepted that two elements are inverse to each other if their product is equal to the identity element: Inverse element in a magma https://en.wikipedia.org/wiki/Inverse_element The definition ...
Alex C's user avatar
  • 1,120
5 votes
0 answers
204 views

Suspicious diagrams on wiki about group-like structures

It seems to me that the diagrams on wiki about group-like structures are not quite right. For example, the following https://en.wikipedia.org/wiki/Monoid#/media/File:Algebraic_structures_-...
ALife's user avatar
  • 274
7 votes
2 answers
551 views

Defining loops: why is divisibility and identitiy implying invertibility?

Wikipedia contains the following figure (to be found, e.g. here) in order to visualize the relations between several algebraic structures. I highlighted a part that I find especially interesting. It ...
M. Winter's user avatar
  • 30.2k
4 votes
1 answer
393 views

Commutative subtraction

It is well known that subtraction is not commutative in general. However, it is commutative in some groups: $\mathbb I$, $\mathbb C_2$, $\mathbb K_4$. I am trying to understand the logic. ...
Alex C's user avatar
  • 1,120
1 vote
0 answers
54 views

Invertibility as Criteria for a Loop

I try to understand the correct criteria for a Loop. I see in Wikipedia https://en.wikipedia.org/wiki/Inverse_element#In_a_unital_magma that “A unital magma in which all elements are invertible is ...
Avichai's user avatar
  • 11