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Comments 1 to 20 out of 8917 in reverse chronological order.

\begin{equation*} \DeclareMathOperator\Coim{Coim} \DeclareMathOperator\Coker{Coker} \DeclareMathOperator\Ext{Ext} \DeclareMathOperator\Hom{Hom} \DeclareMathOperator\Im{Im} \DeclareMathOperator\Ker{Ker} \DeclareMathOperator\Mor{Mor} \DeclareMathOperator\Ob{Ob} \DeclareMathOperator\Sh{Sh} \DeclareMathOperator\SheafExt{\mathcal{E}\mathit{xt}} \DeclareMathOperator\SheafHom{\mathcal{H}\mathit{om}} \DeclareMathOperator\Spec{Spec} \newcommand\colim{\mathop{\mathrm{colim}}\nolimits} \newcommand\lim{\mathop{\mathrm{lim}}\nolimits} \newcommand\Qcoh{\mathit{Qcoh}} \newcommand\Sch{\mathit{Sch}} \newcommand\QCohstack{\mathcal{QC}\!\mathit{oh}} \newcommand\Cohstack{\mathcal{C}\!\mathit{oh}} \newcommand\Spacesstack{\mathcal{S}\!\mathit{paces}} \newcommand\Quotfunctor{\mathrm{Quot}} \newcommand\Hilbfunctor{\mathrm{Hilb}} \newcommand\Curvesstack{\mathcal{C}\!\mathit{urves}} \newcommand\Polarizedstack{\mathcal{P}\!\mathit{olarized}} \newcommand\Complexesstack{\mathcal{C}\!\mathit{omplexes}} \newcommand\Pic{\mathop{\mathrm{Pic}}\nolimits} \newcommand\Picardstack{\mathcal{P}\!\mathit{ic}} \newcommand\Picardfunctor{\mathrm{Pic}} \newcommand\Deformationcategory{\mathcal{D}\!\mathit{ef}} \end{equation*}

On Branislav Sobot left comment #9763 on Lemma 15.128.4 in More on Algebra

It seems to me that you also need to choose so that it is -linearly idependent from , and then also choose to map to . Otherwise, I don't see why the obtained locus doesn't contain .


On Branislav Sobot left comment #9762 on Lemma 10.103.2 in Commutative Algebra

Sorry, but I don't see why the case can't occur. Simply take for some ideal of definition . I think that this lemma is simply wrong in this case, while the case can't occur in the next lemma.


On Sasha left comment #9761 on Section 42.54 in Chow Homology and Chern Classes

"gysin" is a name, so it should be capitalized everywhere.


On Patrick Rabau left comment #9760 on Section 5.22 in Topology

The final paragraph of the proof of Lemma 08ZY refers to Lemma 08ZN with the phrase "the intersection of all open and closed subsets of containing ". That may be ambiguously read to mean the intersection of the collection of all open sets and all closed sets containing , which is not the desired meaning. Using the usual term "clopen set" would make things shorter and clearer.


On Laurent Moret-Bailly left comment #9758 on Section 29.50 in Morphisms of Schemes

In addition to #9757, the expression birational schemes should be defined.


On Fanjun Meng left comment #9757 on Section 29.50 in Morphisms of Schemes

In the paragraph after Definition 29.50.1, it should be "the existence of a birational morphism".


On Félix left comment #9756 on Lemma 10.107.10 in Commutative Algebra

What is K in this context?


On left comment #9755 on Section 10.53 in Commutative Algebra

Maybe we should add the lemma that any product of local rings is the product of the localizations at its maximal ideals.


On left comment #9754 on Section 10.149 in Commutative Algebra

Excellent, I saw other comments about the formula, which is excellent! As a beauty machine manufacturer, Litonlaser is very appreciative.


On Fiasco left comment #9753 on Section 10.149 in Commutative Algebra

Some possible typos in the proof of lemma10.149.1:

line -4:

line -3: , where is the natural quotient map.


On Xiaolong Liu left comment #9752 on Example 15.62.2 in More on Algebra

We need to replace by .


On left comment #9751 on Lemma 52.16.8 in Algebraic and Formal Geometry

Lindo


On left comment #9750 on Lemma 4.19.3 in Categories

For reference, this is Kashiwara, Schapira, Categories and Sheaves, Proposition 3.2.4.


On luciano left comment #9741 on Section 12.16 in Homological Algebra

I think "graduation" should be "gradation". I'm not sure that "graduation" is wrong, many people use it too, but since the page also uses "gradation" I think it's better to stick with that one


On Fiasco left comment #9740 on Section 37.4 in More on Morphisms

How to prove the injectivity of Lemma37.4.2? If we assume is surjective, then it suffices to show is injective by Kummer sequence for etale cohomology.

Since , and are zero, we have and similarly for etale base change. So we have as etale sheaves, where .

Finally we get the desired injection by the spectral sequence


On Chris left comment #9739 on Section 10.53 in Commutative Algebra

perhaps I am missing something, but Lemma 00JA doesn't seem to prove that R is a product of it's localizations at its maximal ideals, just a product of loval artinian rings?


On Chris left comment #9738 on Section 10.53 in Commutative Algebra

perhaps I am missing something, but Lemma 00JA doesn't seem to prove that R is a product of it's localizations at its maximal ideals, just a product of loval artinian rings?


On Olivier Benoist left comment #9737 on Lemma 15.104.5 in More on Algebra

Isn't the consequence that all local rings of A are fields equivalent to the other assertions? (It seems to me that it implies (3)). In this case, it might be useful to state it as a fourth equivalent condition.


On Shubhankar left comment #9718 on Lemma 36.22.1 in Derived Categories of Schemes

Apologies if this is wrong, but why is this not just the projection formula. Currently what the stacksproject calls the projection formula uses that is perfect which is a very strong assumption and not very useful in practice (when one specializes to schemes or algebraic stacks). It might be useful to mention that this formula exists in the projection formula section. Also unless I am mistaken, a similar statement holds for qcqs representable morphisms of algebraic stacks. This is Corollary 4.12 (combined with lemma 2.5) of Hall-Rydh 'Perfect complexes on algebraic stacks'.


On Ayan left comment #9672 on Section 17.29 in Sheaves of Modules

Ctrl+F "topoological"