Fulger–Murayama's characterization of projective space by tangent-sheaf Seshadri constants

Let XX be a smooth projective variety over an algebraically closed field. For a coherent sheaf EE on XX and a point pXp\in X, write ε(E,p)\varepsilon(E,p) for its Seshadri constant at pp. Fulger–Murayama's question. If there exists pXp\in X such that

ε(TX,p)>0,\varepsilon(T_X,p)>0,

then XPnX\simeq \mathbb P^n. This asks whether positivity of the tangent-sheaf Seshadri constant at one point characterizes projective space; the question is posed in analogy with known characterizations using the anticanonical divisor, and its resolution is not given here.

Sources & referencesView supporting material

Primary source

Chih-Wei Chang, “The Seshadri Constants of Tangent Sheaves on Toric Varieties”, arXiv:2211.17172 (2025).

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