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1. • CommentRowNumber1.
   • CommentAuthorzskoda
   • CommentTimeSep 18th 2022
   • PermaLink
   Author: zskoda
   Format: MarkdownItexI tried to edit the entry [[double derivation]] and even if I write a single letter or none (!) it sends back an error > 500 Internal Server Error >Your edit was blocked by spam filtering >Please report this on the nForum in the nLab Technical Matters category. Please give as precise details as you can as to what triggered the error. >nLab home page > Here is the error: > No such file or directory @ rb_sysopen - page_content/submitted_edits/nlab/double_derivation etc. If I try to click on "discuss" button it does NOT open the latest changes page but just links to front page of $n$Forum, not linked to a page.

   I tried to edit the entry double derivation and even if I write a single letter or none (!) it sends back an error

   500 Internal Server Error

   Your edit was blocked by spam filtering

   Please report this on the nForum in the nLab Technical Matters category. Please give as precise details as you can as to what triggered the error.

   nLab home page

   Here is the error:

   No such file or directory @ rb_sysopen - page_content/submitted_edits/nlab/double_derivation

   etc. If I try to click on “discuss” button it does NOT open the latest changes page but just links to front page of $n$Forum, not linked to a page.

2. • CommentRowNumber2.
   • CommentAuthorzskoda
   • CommentTimeSep 18th 2022
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   Author: zskoda
   Format: TextHere is the edited page which I did not succeed to send: Given a _commutative_ [[ring]] $k$ and an associative $k$-algebra $A$ over $k$, the [[tensor product]] $A\otimes_k A$ is equipped with two [[bimodule]] structures, "outer" and "inner". For the outer structure $a\cdot_o(b\otimes c)\cdot_o d = a b\otimes c d$ and for the inner $a\cdot_i(b\otimes c)\cdot_i d = b d\otimes a c$. The two bimodule structures mutually commute. A $k$-linear map $\alpha\in Hom_k(A,A\otimes A)$ is called a __double derivation__ if it is also a map of $A$-bimodules with respect to the _outer_ bimodule structure ($\alpha\in A Mod A({}_A A_A,{}_A A\otimes_k A_A)$); thus the $k$-module $Der(A,A\otimes A)$ of all double derivations becomes an $A$-bimodule with respect to the _inner_ $A$-bimodule structure. The tensor algebra $T_A Der(A,A\otimes A)$ of the $A$-bimodule $Der(A,A\otimes A)$ (which is the [[free monoid]] on $Der(A,A\otimes A)$ in the monoidal category of $A$-bimodules) is a step in the definition of the [[deformed preprojective algebra]]s of [[Bill Crawley-Boevey]]. A theorem of [[Van den Bergh]] says that for any associative $A$ the tensor algebra $T_A Der(A,A\otimes A)$ has a canonical [[double Poisson bracket]]. * Michel Van den Bergh, _Double Poisson algebras_, Trans. Amer. Math. Soc. __360__ (2008) 5711--5769, [arXiv:math.AG/0410528](https://arXiv.org/abs/math/0410528) * Anne Pichereau, Geert Van de Weyer, _Double Poisson cohomology of path algebras of quivers_, J. Alg. __319__, 5 (2008) 2166--2208 [doi](https://doi.org/10.1016/j.jalgebra.2007.09.021) * Jorge A. Guccione, Juan J. Guccione, _A characterization of quiver algebras based on double derivations_, [arXiv:0807.1148](https://arxiv.org/abs/0807.1148) category: algebra

   Here is the edited page which I did not succeed to send:
   
   Given a _commutative_ ring $k$ and an associative $k$-algebra $A$ over $k$, the tensor product $A\otimes_k A$ is equipped with two bimodule structures, "outer" and "inner". For the outer structure $a\cdot_o(b\otimes c)\cdot_o d = a b\otimes c d$ and for the inner $a\cdot_i(b\otimes c)\cdot_i d = b d\otimes a c$. The two bimodule structures mutually commute. A $k$-linear map $\alpha\in Hom_k(A,A\otimes A)$ is called a __double derivation__ if it is also a map of $A$-bimodules with respect to the _outer_ bimodule structure ($\alpha\in A Mod A({}_A A_A,{}_A A\otimes_k A_A)$); thus the $k$-module $Der(A,A\otimes A)$ of all double derivations becomes an $A$-bimodule with respect to the _inner_ $A$-bimodule structure.
   
   The tensor algebra $T_A Der(A,A\otimes A)$ of the $A$-bimodule $Der(A,A\otimes A)$ (which is the free monoid on $Der(A,A\otimes A)$ in the monoidal category of $A$-bimodules) is a step in the definition of the deformed preprojective algebras of Bill Crawley-Boevey. A theorem of Van den Bergh says that for any associative $A$ the tensor algebra $T_A Der(A,A\otimes A)$ has a canonical double Poisson bracket.
   
   * Michel Van den Bergh, _Double Poisson algebras_, Trans. Amer. Math. Soc. __360__ (2008) 5711--5769, [arXiv:math.AG/0410528](https://arXiv.org/abs/math/0410528)
   * Anne Pichereau, Geert Van de Weyer, _Double Poisson cohomology of path algebras of quivers_, J. Alg. __319__, 5 (2008) 2166--2208 [doi](https://doi.org/10.1016/j.jalgebra.2007.09.021)
   * Jorge A. Guccione, Juan J. Guccione, _A characterization of quiver algebras based on double derivations_, [arXiv:0807.1148](https://arxiv.org/abs/0807.1148)
   
   category: algebra
3. • CommentRowNumber3.
   • CommentAuthorzskoda
   • CommentTimeSep 18th 2022
   • PermaLink
   Author: zskoda
   Format: TextCopying the content of [[double derivation]] to another pagename does not work: spam message appears instead of creating a page, including at my personal web. I created [[William Crawley-Boevey]] with redirect [[Bill Crawley-Boevey]] wanted at [[double derivation]] which still shows that [[Bill Crawley-Boevey]] does not exist.

   Copying the content of double derivation to another pagename does not work: spam message appears instead of creating a page, including at my personal web.
   
   I created William Crawley-Boevey with redirect Bill Crawley-Boevey wanted at double derivation which still shows that Bill Crawley-Boevey does not exist.
4. • CommentRowNumber4.
   • CommentAuthorUrs
   • CommentTimeSep 19th 2022
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   Author: Urs
   Format: MarkdownItexHave been busy all day. Am forwarding this to the technical team now...

   Have been busy all day. Am forwarding this to the technical team now…

5. • CommentRowNumber5.
   • CommentAuthorChristian Sattler
   • CommentTimeSep 19th 2022
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   Author: Christian Sattler
   Format: TextThe problem was that "gucci" was a pattern in the spam filter. I've removed it. You should now be able to submit your edit.

   The problem was that "gucci" was a pattern in the spam filter. I've removed it. You should now be able to submit your edit.
6. • CommentRowNumber6.
   • CommentAuthorzskoda
   • CommentTimeSep 20th 2022
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   Author: zskoda
   Format: MarkdownItexUnfortunately, it still seem to persist if I leave "Guccione" so I temporarily wrote G uccione with a space. Then it accepts. * V. Ginzburg, T. Schedler, _Differential operators and BV structures in noncommutative geometry_, Sel. Math. New Ser. 16, 673–730 (2010) [doi](https://doi.org/10.1007/s00029-010-0029-8)

   Unfortunately, it still seem to persist if I leave “Guccione” so I temporarily wrote G uccione with a space. Then it accepts.

   • V. Ginzburg, T. Schedler, Differential operators and BV structures in noncommutative geometry, Sel. Math. New Ser. 16, 673–730 (2010) doi
7. • CommentRowNumber7.
   • CommentAuthorUrs
   • CommentTimeSep 20th 2022
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   Author: Urs
   Format: MarkdownItexOne can work around this problem by escaping some html characters. For example: Guccione gives > Guccione

   One can work around this problem by escaping some html characters. For example:

     Guccione
   

   gives

   Guccione

8. • CommentRowNumber8.
   • CommentAuthorChristian Sattler
   • CommentTimeSep 20th 2022
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   Author: Christian Sattler
   Format: MarkdownItex> Unfortunately, it still seem to persist if I leave “Guccione” Right, I forgot to actually update the deployment. Should be fixed now.

   Unfortunately, it still seem to persist if I leave “Guccione”

   Right, I forgot to actually update the deployment. Should be fixed now.

9. • CommentRowNumber9.
   • CommentAuthorzskoda
   • CommentTimeSep 20th 2022
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   Author: zskoda
   Format: MarkdownItex7 thanks for the tip

   7 thanks for the tip