added historical pointer to:
(That’s the letter that is commonly cited as the historical origin of the term “group”. But re-reading this now, it seems that this letter does not dwell on saying what a “group” is meant to be, but speaks as if author and recipient both already know of and agree on this notion?)
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]]>and these two:
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Added:
The original article that gives a definition equivalent to the modern definition of a group is
linking to pregroup grammar
DavidWhitten
]]>Yes, the definition section is arguably a little lacking there, even though the article redeems itself later, down in Internalization. So I’ve fixed it along these lines.
]]>Minor correction, about “The reason is that two functors…” to change that the natural transformation is between the delooped version of the parallel group homomorphisms, instead of the homomorphisms themselves.
]]>I removed the counterexample which was not about group theory (and clarified the header in counterexamples in algebra).
]]>reformatted the entry group a little, expanded the Examples-section a little and then pasted in the group-related “counterexamples” from counterexamples in algebra. Mainly to indicate how I think this latter entry should eventually be used to improve the entries that it refers to.
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