All Questions
Tagged with derived-algebraic-geometry higher-algebra
25 questions
9
votes
2
answers
803
views
Explanation for Lurie's SAG Remark 25.1.3.7
I am trying to understand the theory of simplicial commutative rings or animated rings. I just find a remark in Lurie's book Spectral Algebraic Geometry:
Remark 25.3.1.7. Let $f : R[x_1,\ldots ,x_n]\...
- 93
3
votes
0
answers
144
views
The assignment of derived infinity category of étale sheaf is an infinity functor?
Consider the ordinary category of schemes $Sch$, for $X\in Sch$, consider the abelian category of étale sheaf with coefficient $\wedge$ as $Mod(X_{ét},\wedge)$, then we can form the derived infinity ...
- 618
1
vote
0
answers
143
views
$\varinjlim_{k}\Omega^{k}\circ \Sigma^{k}$ as 1-excisive approximation of the identity functor
In chapter 6 of HA by Lurie, for any functor $F:C\rightarrow D$ between 'nice' categories (like differentiable infinity categories), there is an $n$ excisive approximation to this functor behaving ...
- 618
2
votes
0
answers
165
views
Square zero extension in the derived setting
Here we take the infinity category of simplicial ring $SCRing=Fun^{\prod}(Poly^{op},Spc)$ and follow the construction 25.3.1.1 in DAG by Lurie, where we extend the construction of square zero ...
- 618
4
votes
1
answer
329
views
Infinite suspension is cotangent complex
In Higher Algebra by Lurie, we define the absolute cotangent complex $L_{A}$ through the composition $C\stackrel{\triangle}{\longrightarrow} Fun(\triangle^{1},C)\stackrel{F}{\longrightarrow}T_{C}$ ...
- 618
1
vote
0
answers
195
views
The spectrum object in the $\infty$ category $CAlg_{R}$
Consider the infinity category of simplicial rings $CAlg=Fun^{\prod}(Poly^{op},Spc)$, and the under-category over $R$: $CAlg_{A/}$ is equivalent to $CAlg_{A}=Fun^{\prod}(Poly^{op}_{R},Spc)$ by 25.1.4....
- 618
2
votes
1
answer
139
views
Construction of Weil restriction in the derived setting
I am currently reading 19.1,2 in SAG by Lurie about Weil restrictions. In the classical case, Weil restriction is the right adjoint to the pullback functor along some morphism $f:X\rightarrow Y$, and ...
- 618
5
votes
0
answers
125
views
Existence of Kan extension for the functor with codomain a complete infinity category
I am currently reading this paper on derived blow up, in definition 2.4.1, I am faced with such situation:
if we denote the infinity category of simplicial ring as $Alg$ and the 1 category of ...
- 618
4
votes
1
answer
548
views
Does derived tensor product preserve fiber sequence？
In lemma 3.1.5 of this paper I read, there is a fiber sequence of the underlying spaces of simplicial commutative rings $A\stackrel{f}{\longrightarrow} A\rightarrow A/\!\!/f$. Here we define the "...
- 618
3
votes
0
answers
196
views
Divided power structure on $E_\infty$-algebras?
Let $A$ be a simplicial commutative ring, then it is known that the ideal of elements of degree $\ge1$ in the associated CDGA has a "DG divided power structure," which induces a divided ...
- 371
5
votes
1
answer
534
views
Animated rings and $\mathbb E_{\infty}$-rings
Let $R$ be a discrete commutative ring. The Proposistion 25.1.2.4 in Lurie's Spectral Algebraic Geometry says that the natural functor from the $\infty$-category of animated $R$-algebras to the $\...
- 151
8
votes
1
answer
324
views
$\infty$-categorical enhancement of $\mathsf{D}_\mathsf{B}(\mathsf{A})$
In this question, it is asked why we like to consider $\mathsf{D}_\textrm{qc}(X)$ rather than $\mathsf{D}(\mathsf{QCoh}(X)).$ Professor Cisinski answers rather convincingly that the $\infty$-...
- 1,349
2
votes
0
answers
235
views
Formally étale maps of animated $k$-algebras
In Lurie's DAG, he defines what it means for a natural transformation $T:\mathcal{F}\to\mathcal{F}'$ of functors $\mathcal{F},\mathcal{F}':\mathcal{SCR}\to\mathcal{S}$ to be formally étale. Namely, it ...
- 301
5
votes
1
answer
298
views
Interpolating between the flat and smooth affine lines in spectral algebraic geometry
Consider the following construction (which came up recently in a question about "spectral exterior algebras"):
Pick a ring spectrum $R$ and consider the $\infty$-category $\mathsf{Mod}_R$ ...
- 11.8k
3
votes
0
answers
213
views
Base-change theorems for stable $\infty$-categories
Omitting some technicalities, the base-change theorem for quasicoherent sheaves says that if we have the following diagram of (derived) schemes
$\require{AMScd}$
\begin{CD}
X \times_S Y @>\pi_2>&...
- 2,356
5
votes
1
answer
321
views
Is there a definition of reduced $E_\infty$ ring?
[Edit: I have completely changed the question in response to the replies given]
I am curious if there is well defined notion of reduced $E_\infty$-ring.
Let $CAlg$ denote the $\infty$-category of $E_\...
- 448
9
votes
2
answers
380
views
How to characterize $E_n$ morphisms from $\mathrm{Mod}(A)$ to $\mathrm{Mod}(B)$?
Suppose $A$ and $B$ are $E_{\infty}$ rings, then $\mathrm{Mod}(A)$ and $\mathrm{Mod}(B)$ are $E_{\infty}$ monoidal categories (left modules over those rings). We can ask about $E_n$ colimit-preserving ...
- 2,356
5
votes
1
answer
450
views
Does formation of the derived $\infty$-category preserve pushouts?
Let $B\leftarrow A\to C$ be a diagram of commutative rings, and let $\mathcal{D}(A)$ be the derived $\infty$-category of $A$-modules (as in Lurie's "Higher Algebra"). Then is there an ...
- 1,349
3
votes
1
answer
368
views
Is the category of spectra on $\mathbb{P}^1$ a module category?
I cannot really state my question in an incredibly precise way as I'm very new to this area, but I hope what I'm asking will be clear. Let $\mathcal{C}$ be the infinity category of sheaves of quasi-...
- 2,356
6
votes
0
answers
1k
views
Examples of Lurie tensor product computations
I am interested in examples of computing the Lurie tensor product.
For example, if $A$ and $B$ are connective DG algebras (over $\mathbb{Z}$, say), then I think there is an equivalence $A\text{-mod} \...
- 61
16
votes
1
answer
1k
views
$\infty$-operads and $E_\infty$-algebras
I work in algebraic geometry. Lately, the answer to most of my questions seems to be "you should read Lurie's Higher Algebra." I took this advice seriously, however it turned out not to be an easy ...
- 16.2k
35
votes
2
answers
3k
views
What is the relationship between connective and nonconnective derived algebraic geometry?
"Derived algebraic geometry" usually means the study of geometry locally modeled on "$Spec R$" where $R$ is a connective $E_\infty$ ring spectrum (perhaps with further restrictions). Why "connective", ...
- 64k
2
votes
0
answers
268
views
Interesting examples of large, accessible, non-presentable $\infty$-categories?
What are some interesting examples of accessible $\infty$-categories
which are not presentable and not small?
By interesting I mean a category which comes up naturally in a certain context and in a ...
- 7,799
2
votes
0
answers
157
views
Why is the stabilization of augmented $\mathbb{E}_\infty$-algebras equivalent to $k$-module spectra?
(I have already asked this on Math.SE, but it didn't draw much attention there, so I am reposting it here.)
Example 1.1.4 of Jacob Lurie's DAGX says that the stabilization $\operatorname{Stab}((\...
- 95
3
votes
1
answer
465
views
Monoidal Forgetful/Free Adjunction for $E_2$-algebras
Suppose I am given two $E_2$-ring spectra $A$ and $B$ and a morphism of $E_2$-rings $\phi:A\to B$. Then I have $E_1$-monoidal categories of modules $LMod_A$ and $LMod_B$. Moreover I have morphisms $F:...
- 10.5k