4 citations · 13 across the 15 of their papers we have counts for
15 papers
Ekedahl-Oort strata under natural embeddings of orthogonal and unitary Shimura varieties
Yan Qijun, Zhang Chao
In this paper, we study the behavior of Ekedahl-Oort strata under natural embeddings between the good reductions modulo of GSpin Shimura varieties and Rapoport-Smithling-Zhang…
A relation between zip stacks and moduli stacks of truncated local shtukas
Qijun Yan
Let \(G\) be a reductive group over a field \(k\), and let \(μ\) be a cocharacter of \(G\). We prove that Viehmann's double coset spaces associated with \((G, μ)\) are representabl…
Partial-twuality polynomials of delta-matroids
Qi Yan, Xian'an Jin
Gross, Mansour and Tucker introduced the partial-twuality polynomial of a ribbon graph. Chumutov and Vignes-Tourneret posed a problem: it would be interesting to know whether the p…
Twist monomials of binary delta-matroids
Qi Yan, Xian'an Jin
Recently, we introduced the twist polynomials of delta-matroids and gave a characterization of even normal binary delta-matroids whose twist polynomials have only one term and pose…
An alternative construction of zip period maps for Shimura varieties
Qijun Yan
Let be the special fibre of a Shimura variety of Hodge type, with good reduction at a place above . We give an alternative construction of the zip period map for , which…
Twist polynomials of delta-matroids
Qi Yan, Xian'an Jin
Recently, Gross, Mansour and Tucker introduced the partial duality polynomial of a ribbon graph and posed a conjecture that there is no orientable ribbon graph whose partial dualit…
The Ihara-zeta function and the spectrum of the join of two semi-regular bipartite graphs
Xiaotong Li, Xian'an Jin, Qi Yan
In this paper, using matrix techniques, we compute the Ihara-zeta function and the number of spanning trees of the join of two semi-regular bipartite graphs. Furthermore, we show t…
Partial-dual genus polynomials and signed intersection graphs
Qi Yan, Xian'an Jin
Recently, Gross, Mansour and Tucker introduced the partial-dual genus polynomial of a ribbon graph as a generating function that enumerates the partial duals of the ribbon graph by…
Counterexamples to the interpolating conjecture on partial-dual genus polynomials of ribbon graphs
Qi Yan, Xian'an Jin
Gross, Mansour and Tucker introduced the partial-dual orientable genus polynomial and the partial-dual Euler genus polynomial. They showed that the partial-dual genus polynomial fo…
Excluded checkerboard colourable ribbon graph minors
Xia Guo, Xian'an Jin, Qi Yan
In this paper, we first introduce the notions of checkerboard colourable minors for ribbon graphs motivated by the Eulerian ribbon graph minors, and two kinds of bipartite minors f…
Counterexamples to conjectures by Gross, Mansour and Tucker on partial-dual genus polynomials of ribbon graphs
Qi Yan, Xian'an Jin
Gross, Mansour and Tucker introduced the partial-dual orientable genus polynomial and the partial-dual Euler genus polynomial. They computed these two partial-dual genus polynomial…
Eulerian and bipartite binary delta-matroids
Qi Yan, Xian'an Jin
Delta-matroid theory is often thought of as a generalization of topological graph theory. It is well-known that an orientable embedded graph is bipartite if and only if its Petrie…
Characterization of regular checkerboard colourable twisted duals of ribbon graphs
Xia Guo, Xian'an Jin, Qi Yan
The geometric dual of a cellularly embedded graph is a fundamental concept in graph theory and also appears in many other branches of mathematics. The partial dual is an essential…
Checkerboard colourable twisted duals
Qi Yan, Xian'an Jin
In this note we show that any embedded graph has a checkerboard colourable twisted dual and any Eulerian embedded graph has a checkerboard colourable partial Petrial, answering que…
Ekedahl-Oort stratifications of Shimura varieties via Breuil-Kisin windows
Qijun Yan
Let be the special fibre of the good reduction of a Shimura variety of Hodge type. By constructing adapted deformations for the associated -divisible groups of , we m…