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1. • CommentRowNumber1.
   • CommentAuthorUrs
   • CommentTimeOct 8th 2012
   • (edited Oct 8th 2012)
   • PermaLink
   Author: Urs
   Format: MarkdownItexI have touched the formatting at _[[free groupoid]]_. Then I added the statement that the fundamental groups of a free groupoid are free. Also added a pointer to a writeup of the proof.

   I have touched the formatting at free groupoid. Then I added the statement that the fundamental groups of a free groupoid are free. Also added a pointer to a writeup of the proof.

2. • CommentRowNumber2.
   • CommentAuthorzskoda
   • CommentTimeOct 9th 2012
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   Author: zskoda
   Format: MarkdownItexJust unimportant question: is there an analogue of [[Fox derivative]] for free groupoids considered anywhere (Fox derivative is originally defined for group algebras of free groups) ?

   Just unimportant question: is there an analogue of Fox derivative for free groupoids considered anywhere (Fox derivative is originally defined for group algebras of free groups) ?

3. • CommentRowNumber3.
   • CommentAuthorTim_Porter
   • CommentTimeOct 9th 2012
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   Author: Tim_Porter
   Format: MarkdownItexYes. Ronnie, with Phil Higgins did something on those lines and I think it is in the triple authored book.

   Yes. Ronnie, with Phil Higgins did something on those lines and I think it is in the triple authored book.

4. • CommentRowNumber4.
   • CommentAuthorronniegpd
   • CommentTimeJun 24th 2015
   • (edited Jun 24th 2015)
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   Author: ronniegpd
   Format: TextThe question concerns the relation between crossed complexes and chain complexes with a groupoid of operators which is fully discussed in the book partially titled "Nonabelian Algebraic Topology". See Sections 7.4, 8.4, 9.5.

   The question concerns the relation between crossed complexes and chain complexes with a groupoid of operators which is fully discussed
   in the book partially titled "Nonabelian Algebraic Topology". See Sections 7.4, 8.4, 9.5.
5. • CommentRowNumber5.
   • CommentAuthorUrs
   • CommentTimeApr 28th 2023
   • PermaLink
   Author: Urs
   Format: MarkdownItexadded a sentence and diagram ([here](https://ncatlab.org/nlab/show/free+groupoid#FreeGroupoidOnACategory)) relating to the more general construction of the free groupoid on general (small strict) categories (i.e. not necessarily on free categories, as was previously implicitly assumed) also added cross-link with the other adjoint, the *[[core]]* <a href="https://ncatlab.org/nlab/revision/diff/free+groupoid/11">diff</a>, <a href="https://ncatlab.org/nlab/revision/free+groupoid/11">v11</a>, <a href="https://ncatlab.org/nlab/show/free+groupoid">current</a>

   added a sentence and diagram (here) relating to the more general construction of the free groupoid on general (small strict) categories (i.e. not necessarily on free categories, as was previously implicitly assumed)

   also added cross-link with the other adjoint, the core

   diff, v11, current

6. • CommentRowNumber6.
   • CommentAuthorUrs
   • CommentTimeMay 29th 2023
   • PermaLink
   Author: Urs
   Format: MarkdownItexadded pointer to: * [[Saunders MacLane]], p. 51 Exp. 3 in: *[[Categories for the Working Mathematician]]*, Springer (1971) &lbrack;[doi:10.1007/978-1-4757-4721-8](https://link.springer.com/book/10.1007/978-1-4757-4721-8)&rbrack; <a href="https://ncatlab.org/nlab/revision/diff/free+groupoid/12">diff</a>, <a href="https://ncatlab.org/nlab/revision/free+groupoid/12">v12</a>, <a href="https://ncatlab.org/nlab/show/free+groupoid">current</a>

   added pointer to:

   • Saunders MacLane, p. 51 Exp. 3 in: Categories for the Working Mathematician, Springer (1971) [doi:10.1007/978-1-4757-4721-8]

   diff, v12, current

7. • CommentRowNumber7.
   • CommentAuthorUrs
   • CommentTimeMay 31st 2023
   • PermaLink
   Author: Urs
   Format: MarkdownItexadded pointer to: * [[William Dwyer]], [[Daniel Kan]], §5.5 of: *Simplicial localizations of categories*, J. Pure Appl. Algebra **17** 3 (1980), 267-284 &lbrack;<a href="https://doi.org/10.1016/0022-4049(80)90049-3">doi:10.1016/0022-4049(80)90049-3</a>, [pdf](http://www.nd.edu/~wgd/Dvi/SimplicialLocalizations.pdf)&rbrack; <a href="https://ncatlab.org/nlab/revision/diff/free+groupoid/15">diff</a>, <a href="https://ncatlab.org/nlab/revision/free+groupoid/15">v15</a>, <a href="https://ncatlab.org/nlab/show/free+groupoid">current</a>

   added pointer to:

   • William Dwyer, Daniel Kan, §5.5 of: Simplicial localizations of categories, J. Pure Appl. Algebra 17 3 (1980), 267-284 [doi:10.1016/0022-4049(80)90049-3, pdf]

   diff, v15, current

8. • CommentRowNumber8.
   • CommentAuthorUrs
   • CommentTimeMay 31st 2023
   • PermaLink
   Author: Urs
   Format: MarkdownItexadded pointer to: * [[Pierre Gabriel]], [[Michel Zisman]], §1.5.4 of: *[[Calculus of fractions and homotopy theory]]* Ergebnisse der Mathematik und ihrer Grenzgebiete **35**, Springer (1967) &lbrack;[doi:10.1007/978-3-642-85844-4](https://link.springer.com/book/10.1007/978-3-642-85844-4), [pdf](https://web.math.rochester.edu/people/faculty/doug/otherpapers/GZ.pdf)&rbrack; <a href="https://ncatlab.org/nlab/revision/diff/free+groupoid/16">diff</a>, <a href="https://ncatlab.org/nlab/revision/free+groupoid/16">v16</a>, <a href="https://ncatlab.org/nlab/show/free+groupoid">current</a>

   added pointer to:

   • Pierre Gabriel, Michel Zisman, §1.5.4 of: Calculus of fractions and homotopy theory Ergebnisse der Mathematik und ihrer Grenzgebiete 35, Springer (1967) [doi:10.1007/978-3-642-85844-4, pdf]

   diff, v16, current