Formal Poincare polynomial conjecture for torus actions

Let VV be a projective algebraic variety over kk with an action of a torus TT such that the fixed-point set VTV^{T} and the set VT,1V^{T,1} of one-dimensional TT-orbits are finite. Let Γ\Gamma be the graph whose vertices are VTV^{T} and whose edges correspond to one-dimensional TT-orbits. For a total order o\mathfrak{o} on the vertices, orient each edge from the greater vertex to the smaller one, and let nvon^{\mathfrak{o}}_{v} be the number of arrows with source vv. Define

b2io=#{vΓ:nvo=i},Po(t)=ib2iot2i.b^{\mathfrak{o}}_{2i}=\#\{v\in\Gamma:n^{\mathfrak{o}}_{v}=i\},\qquad P^{\mathfrak{o}}(t)=\sum_i b^{\mathfrak{o}}_{2i}t^{2i}.

Let PV(t)P_V(t) be the Poincare polynomial of VV.

Formal Poincare polynomial conjecture.

PV(t)=mino{Po(t)},P_V(t)=\min_{\mathfrak{o}}\{P^{\mathfrak{o}}(t)\},

where o\mathfrak{o} ranges over all total orders on the vertices of Γ\Gamma.

This conjecture seeks to recover the ordinary cohomology of a cohomologically pure projective variety from the fixed points and one-dimensional orbits of a torus action. Its general status is open.

Sources & referencesView supporting material

Primary source

Zongbin Chen, “Truncated affine grassmannians and truncated affine Springer fibers for GL_3”, arXiv:1401.1930 (2014).

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