Peng Zhou

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blog:2022-12-14

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2022-12-14 Wed

  • Cross my t and dot my i.

T and I branes

\gdef\End{\text{End}}

Let me be super careful, and state the condition that I need.

Let XX be a Weinstein manifold. Let TpT_p be a collection of cocores, one for each critical point of the psh function φ\varphi. Let IpI_p be the collection of cores. We have Hom(Ip,Tq)=δp,q\Hom(I_p, T_q) = \delta_{p,q}, and similarly Hom(Tp,Iq)=δpq[n]\Hom(T_p, I_q) = \delta_{pq}[-n].

We assume that our skeleton is a union of smooth Lagrangians. This is true in the case of cotangent bundle, or in the case of plumbing of cotangent bundles.

We can ask, if every object in the wrapped Fukaya category can be expressed as a finite twisted complex of the cocores. CDGG says yes.

If you give me a Lagrangian LL, then I will intersect it with the core. I assume the intersection is transverse.

If I am brave enough, I will take the core as a Lagrangian, and I allow disk to end on it, as if my core is a smooth Lagrangian.

How to remember the given Lagrangian LL. I first, remember the intersections between II and LL. But, that's not good enough. There are disks bounding the core and LL.

Consider the example, where I=SnI = S^n, and L=SnL =S^n perturbed. The intersection ILI \cap L are two points. There is a morphism γEndn+1(T)=Cn1(ΩSn)\gamma \in \End^{-n+1}(T) = C_{n-1}(\Omega S^n). The fundamental class of Sn1S^{n-1} corresponds to γ\gamma. Now, consider endomorphism of that complex, we have End(T[n]+T)Hom(T,T[n])=End(T)[n]γ[n] \End( T[-n] + T) \supset \Hom(T, T[-n]) = \End(T)[-n] \ni \gamma[-n] Here γ[n]\gamma[-n] is a degree 11 map.

There is no rigid holomorhpic disks, that bounds LL and II, and create a differential for the bottom degree guy, to the top one. In the case of S1S^1, we have two disks, worth S0S^0. In the case of S2S^2, we have S1S^1-family of disks from bottom intersection to the top one. But, that information is not remembered by the usual rigid disks.

What are we doing? The Lagrangian LL evaluate out a collection of 'path on the core'. Given a collection of TT branes with bounding cochains, we can also get a collection of paths on the core. The requirement is that, TT and LL intersects II at the same points.

Now, the first layer, shall we do TiHom(Ii,L)T_i \otimes \Hom(I_i, L). Here, I am not just taking pILTp[dp]\oplus_{p \in I \cap L} T_p[d_p]. Wait, I think it is OK, we can do that. Pretend, we are computing the AA_\infty structure of Hom(I,L)\Hom(I, L), we will first count the intersection points, and build the chain complex, but here, for an intersection point pp, instead of putting just we also include the factor TpT_p tensor with C[dp]\C[-d_p].

Are we just trying to get the End(I)\End(I) module structure of LL? Suppose II is a single smooth compact Lagrangian. It is a funny adjoint, we want to probe with II, but we want to output with TT.

So, we are looking at structure of TEnd(T)Hom(T,I)End(I)Hom(I,L) T \otimes_{\End(T)} \Hom(T, I) \otimes_{\End(I)} \Hom(I, L) whatever the output is. Or, we can do TEnd(T)HomEnd(I)(Hom(I,T),Hom(I,L)) T \otimes_{\End(T)} \Hom_{\End(I)}(\Hom(I, T),\Hom(I, L))

Now, let's test if it works on I=S2,L=S2I = S^2, L = S^2. Well, Hom(I,L)\Hom(I, L), cohomologically, is just the free End(I)\End(I) module. We just use a holomorphic disk. Not quite enough.

One need higher dimensional moduli space of disks.

Well, a family of disks is a family of disks, there is no way out. We are no longer doing just 1 or 0 dimensional disks counting. Good bye. We could introduce more strata in the middle, If we have Maslov indices of the two points, differ by kk, then the moduli of disks going between them should be of dimension kk as well, R×Nk1\R \times N^{k-1}, something like that.

What's the story of a torus? We look at the Morse gradient flowline. Do we have higher degree morphisms between TT branes? This time, no.

Here is a formula

\gdef\End{\text{End}} TEnd(T)HomEnd(I)(Hom(I,T),Hom(I,L)) T \otimes_{\End(T)} \Hom_{\End(I)}(\Hom(I, T),\Hom(I, L))

In principle, this should work, since we are doing nothing more than Koszul duality. For example, in the cotangent bundle case, if we do L=TL=T, then we should get back HomEnd(I)(Hom(I,T),Hom(I,T))=Hom(T,T)\Hom_{\End(I)}(\Hom(I, T),\Hom(I, T)) = \Hom(T, T).

blog/2022-12-14.1671123742.txt.gz · Last modified: 2023/06/25 15:53 (external edit)