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Questions tagged [nearby-cycles]

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2 votes
0 answers
74 views

Lift of nearby cycles functor

Let $S$ be the spectrum of a Henselian discrete valuation ring (called a Henselian trait). Let $f:X\to S$ be a finite type, separated morphism of schemes. Let $\eta\in S$ be the generic point. Let $s\...
Doug Liu's user avatar
  • 545
4 votes
2 answers
467 views

Nearby cycles for stacks

Let $X$ be a variety over $\mathbb C$. Let $f\colon X \to \mathbb{A}^1$ be a regular function. I understand that there is an analytic nearby cycles functor, defined in terms of the exponential map. I ...
user492133's user avatar
1 vote
0 answers
156 views

Definition of nearby cycle over an affine line

In some famous papers like Gaitsgory's "Construction of central elements in the affine Hecke algebra via nearby cycles" and Beilinson-Bernstein's "A proof of Jantzen conjectures", ...
Allen Lee's user avatar
  • 271
3 votes
0 answers
197 views

Nearby cycles of a constant $\Lambda$-sheaf

Let $X$ be a scheme over a henselian trait $S = (S,s,\eta)$. Let $\ell$ be a prime number which is invertible on $S$ and let $\Lambda := \mathbb Z_{\ell}/\ell^k\mathbb Z_{\ell}$ where $k\geq 1$. Let $\...
Suzet's user avatar
  • 717
1 vote
0 answers
51 views

Nearby cycles morphism of Guibert-Loeser-Merle

In the paper Iterated vanishing cycles, convolution, and a motivic analogue of a conjecture of Steenbrink by Gil Guibert, Francois Loeser and Michel Merle, the authors defined the morphism for which I ...
Alexey Do's user avatar
  • 823