Implement the cohomology ring of a right-angled Artin group

[tscrim]

Since they have nice structure corresponding to a quotient of an exterior algebra.

Component: group theory

Keywords: cohomology

Author: Travis Scrimshaw

Branch/Commit: 0c4107c

Reviewer: Frédéric Chapoton

Issue created by migration from https://trac.sagemath.org/ticket/29698

[tscrim]

Commit: f33b09b

[tscrim]

Branch: public/groups/raag_cohomology-29698

[tscrim]

New commits:

f33b09b

Implementation of the cohomology ring of a RAAG.

[fchapoton]

comment:2

reminds me of #27874

[tscrim]

comment:3

It does have the hints of that as the trace monoid is the monoid version of a right-angled Artin group. Although this implementation is quite different IMO.

[fchapoton]

comment:4

some pyflakes warning, see patchbot reports

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

abd76f4	Merge branch 'public/groups/raag_cohomology-29698' of git://trac.sagemath.org/sage into public/groups/raag_cohomology-29698
966ae57	Fixing pyflakes warnings.

[sagetrac-git]

Changed commit from f33b09b to 966ae57

[tscrim]

comment:6

Fixed.

[fchapoton]

comment:7

Do you need to use len in these tests ?

+        if len(m) == 0:
+            return '1'
+        term = ''
+        for i in m:
+            if len(term) != 0:
+                term += '*'
+            term += 'e' + str(i)
+        return term

[sagetrac-git]

Changed commit from 966ae57 to 0c4107c

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

0c4107c

Using join and faster bool check in RAAG cohomology.

[tscrim]

comment:9

Indeed, I do not. I can also use join() as well.

[tscrim]

comment:10

Green patchbot.

[fchapoton]

Reviewer: Frédéric Chapoton

[fchapoton]

comment:11

Looks good.
I am just so slightly worried about the pdf doc, but was not able to check that it works.
Let me give a positive review nevertheless.

[tscrim]

comment:12

Replying to @fchapoton:

Looks good.
I am just so slightly worried about the pdf doc, but was not able to check that it works.
Let me give a positive review nevertheless.

Thanks. The pdf doc built for me without any problems.

[vbraun]

Changed branch from public/groups/raag_cohomology-29698 to 0c4107c