added pointer to:

- Anthony Knapp,
*Basic Algebra*, Springer (2006) [doi:10.1007/978-0-8176-4529-8, pdf]

added pointer to:

- Joseph A. Gallian,
*Contemporary Abstract Algebra*, Chapman and Hall/CRC (2020) [doi:10.1201/9781003142331, webpage, pdf]

added pointer to:

- Paolo Aluffi,
*Algebra: Chapter 0*, Graduate Studies in Mathematics**104**, AMS (2009) [ISBN:978-1-4704-1168-8]

I tweaked the Idea-sentence a little.

Very good, thanks.

]]>Thanks for your additions. Todd! I added a brief “Idea”-sentence. Maybe that needs improvement, though… :-)

]]>Edit: I’m generally not fond of the practice of defining a concept as a special case of a more complicated concept, as for example an algebra over an operad defined as a one-object category over an operad. Or, at least make such definitions secondary.

Exactly, I am not a fan of that either. That’s why I am saying: these entries need sombody to take care of them. I think the previous one was written in a haste and therefore just pointed to “category over an operad”.

]]>Edit: I'm generally not fond of the practice of defining a concept as a special case of a more complicated concept, as for example an algebra over an operad defined as a one-object category over an operad. Or, at least make such definitions secondary. ]]>

the topic-cluster “algebra” is stiil a little orphaned on the Lab, I find. I added a bit to

but these entries are still a bit pitiful. Maybe somebody feels challenged to turn them into good entries. Especially the latter.

Should we have pages algebra over a Lawvere theory, algebra over a PROP, etc? Some entries look like they want such links (for instance algebra itself).

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