Query：
学者姓名：侯建锋
Refining：
Year
Type
Indexed by
Source
Complex
Former Name
Co-
Language
Clean All
Abstract ：
Let F be a family of r-uniform hypergraphs (henceforth r-graphs). An F-saturated r-graph is a maximal r-graph not containing any member of F as a subgraph. For integers l >= r >= 2, let K-l+1(r) be the collection of all r-graphs F with at most ((l+1)(2)) edges such that for some (l+1)-set S every pair {u,v} subset of S is covered by an edge in F, and let T-r(n,l) be the complete l-partite r-graph on n vertices with no two part sizes differing by more than one. Let t(r)(n,l) be the number of edges in T-r(n,l). Our first result shows that for each l >= r >= 2 every K-l+1(r)-saturated r-graph on n vertices with t(r)(n,l)-o(n(r-1+1/l)) edges contains a complete l-partite subgraph on (1-o(1))n vertices, which extends a stability theorem for Kl+1-saturated graphs given by Popielarz, Sahasrabudhe, and Snyder. We also show that the bound is best possible. Our second result is motivated by a celebrated theorem of Andr & aacute;sfai, Erdos, and S & oacute;s, which states that for l >= 2 every Kl+1-free graph G on n vertices with minimum degree delta(G) > 3l-4/3l-1 n is l-partite. We give a hypergraph version of it. The minimum positive co-degree of an r-graph H, denoted by delta(+)(r-1)(H), is the maximum k such that if S is an (r-1)-set contained in an edge of H, then S is contained in at least k distinct edges of H. Let l >= 3 be an integer and H be a K-l+1(3)-saturated 3-graph on n vertices. We prove that if either l >= 4 and delta(+)(2)(H)>3l-7/3l-1 n; or l=3 and delta(+)(2)(H)>2n/7, then H is l-partite; and the bound is best possible. This is the first stability result on minimum positive co-degree for hypergraphs.
Keyword ：
hypergraph hypergraph positive co-degree positive co-degree saturation saturation stability stability
Cite：
Copy from the list or Export to your reference management。
| GB/T 7714 | Hou, Jianfeng , Li, Heng , Yang, Caihong et al. Two Stability Theorems for Kl+1r-Saturated Hypergraphs [J]. | JOURNAL OF GRAPH THEORY , 2025 , 109 (4) : 492-504 . |
| MLA | Hou, Jianfeng et al. "Two Stability Theorems for Kl+1r-Saturated Hypergraphs" . | JOURNAL OF GRAPH THEORY 109 . 4 (2025) : 492-504 . |
| APA | Hou, Jianfeng , Li, Heng , Yang, Caihong , Zeng, Qinghou , Zhang, Yixiao . Two Stability Theorems for Kl+1r-Saturated Hypergraphs . | JOURNAL OF GRAPH THEORY , 2025 , 109 (4) , 492-504 . |
| Export to | NoteExpress RIS BibTex |
Version ：
Abstract ：
For a nondegenerate r-graph F, large n, and t in the regime [0, c(F)n], where c(F)>0 is a constant depending only on F, we present a general approach for determining the maximum number of edges in an n-vertex r-graph that does not contain t+1 vertex-disjoint copies of F. In fact, our method results in a rainbow version of the above result and includes a characterization of the extremal constructions. Our approach applies to many well-studied hypergraphs (including graphs) such as the edge-critical graphs, the Fano plane, the generalized triangles, hypergraph expansions, the expanded triangles, and hypergraph books. Our results extend old results of Erdos [13], Simonovits [76], and Moon [58] on complete graphs, and can be viewed as a step toward a general density version of the classical Corradi-Hajnal [10] and Hajnal-Szemeredi [32] theorems. Our method relies on a novel understanding of the general properties of nondegenerate Turan problems, which we refer to as smoothness and boundedness. These properties are satisfied by a broad class of nondegenerate hypergraphs and appear to be worthy of future exploration.
Keyword ：
F-matching F-matching Hypergraph Turan problems Hypergraph Turan problems stability stability the Corr & aacute;di-Hajnal theorem the Corr & aacute;di-Hajnal theorem vertex-extendability vertex-extendability
Cite：
Copy from the list or Export to your reference management。
| GB/T 7714 | Hou, Jianfeng , Li, Heng , Liu, Xizhi et al. A step towards a general density Corradi-Hajnal theorem [J]. | CANADIAN JOURNAL OF MATHEMATICS-JOURNAL CANADIEN DE MATHEMATIQUES , 2025 . |
| MLA | Hou, Jianfeng et al. "A step towards a general density Corradi-Hajnal theorem" . | CANADIAN JOURNAL OF MATHEMATICS-JOURNAL CANADIEN DE MATHEMATIQUES (2025) . |
| APA | Hou, Jianfeng , Li, Heng , Liu, Xizhi , Yuan, Long-Tu , Zhang, Yixiao . A step towards a general density Corradi-Hajnal theorem . | CANADIAN JOURNAL OF MATHEMATICS-JOURNAL CANADIEN DE MATHEMATIQUES , 2025 . |
| Export to | NoteExpress RIS BibTex |
Version ：
Abstract ：
Given an r-graph F with r >= 2, let ex(n,(t+1)F) denote the maximum number of edges in an n-vertex r-graph with at most t pairwise vertex-disjoint copies of F. Extending several old results and complementing prior work [34] on nondegenerate hypergraphs, we initiate a systematic study on ex(n,(t+1)F) for degenerate hypergraphs F. For a broad class of degenerate hypergraphs F, we present near-optimal upper bounds for ex(n,(t+1)F) when n is sufficiently large and t lies in intervals [0,epsilon & sdot;ex(n,F)/n(r-1)], [ex(n,F)epsilon n(r-1),epsilon n], and [(1-epsilon)nv(F),nv(F)], where epsilon>0 is a constant depending only on F. Our results reveal very different structures for extremal constructions across the three intervals, and we provide characterizations of extremal constructions within the first interval. Additionally, we characterize extremal constructions within the second interval for graphs. Our proof for the first interval also applies to a special class of nondegenerate hypergraphs, including those with undetermined Tur & aacute;n densities, partially improving a result in [34]. (c) 2025 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).
Keyword ：
Corr & aacute;di-Hajnal theorem Corr & aacute;di-Hajnal theorem Degenerate hypergraphs Degenerate hypergraphs Hajnal-Szemer & eacute;di theorem Hajnal-Szemer & eacute;di theorem Tiling problem Tiling problem
Cite：
Copy from the list or Export to your reference management。
| GB/T 7714 | Hou, Jianfeng , Hu, Caiyun , Li, Heng et al. Toward a density Corrádi-Hajnal theorem for degenerate hypergraphs [J]. | JOURNAL OF COMBINATORIAL THEORY SERIES B , 2025 , 172 : 221-262 . |
| MLA | Hou, Jianfeng et al. "Toward a density Corrádi-Hajnal theorem for degenerate hypergraphs" . | JOURNAL OF COMBINATORIAL THEORY SERIES B 172 (2025) : 221-262 . |
| APA | Hou, Jianfeng , Hu, Caiyun , Li, Heng , Liu, Xizhi , Yang, Caihong , Zhang, Yixiao . Toward a density Corrádi-Hajnal theorem for degenerate hypergraphs . | JOURNAL OF COMBINATORIAL THEORY SERIES B , 2025 , 172 , 221-262 . |
| Export to | NoteExpress RIS BibTex |
Version ：
Abstract ：
For many well-known families of triple systems M, there are perhaps many near-extremal M-free configurations that are far from each other in edit-distance. Such a property is called non-stable and is a fundamental barrier to determining the Turan number of M. Liu and Mubayi gave the first finite example that is non-stable. In this paper, we construct another finite family of triple systems M such that there are two near-extremal M-free configurations that are far from each other in edit-distance. We also prove its Andrasfai-Erdos-Sos type stability theorem: Every M-free triple system whose minimum degree is close to the average degree of the extremal configurations is a subgraph of one of these two near-extremal configurations. As a corollary, our main result shows that the boundary of the feasible region of M has exactly two global maxima.
Cite：
Copy from the list or Export to your reference management。
| GB/T 7714 | Zhang, Yixiao , Hou, Jianfeng , Li, Heng . A 2-stable family of triple systems [J]. | ELECTRONIC JOURNAL OF COMBINATORICS , 2024 , 31 (2) . |
| MLA | Zhang, Yixiao et al. "A 2-stable family of triple systems" . | ELECTRONIC JOURNAL OF COMBINATORICS 31 . 2 (2024) . |
| APA | Zhang, Yixiao , Hou, Jianfeng , Li, Heng . A 2-stable family of triple systems . | ELECTRONIC JOURNAL OF COMBINATORICS , 2024 , 31 (2) . |
| Export to | NoteExpress RIS BibTex |
Version ：
Abstract ：
Given two graphs H and F, the maximum possible number of copies of H in an F-free graph on n vertices is denoted by ex(n, H, F). Let l F denote t vertex disjoint copies of F. Gy6ri and Li (2012) obtained results on ex(n, C-3, C2k+1), which was further improved by Alon and Shikhelman (2016). In this paper, we determine the exact value of ex(n, C-3, B C2k+1) and its extremal graph for all l >= 2 and large n. (c) 2024 Elsevier B.V. All rights reserved.
Keyword ：
Cycle Cycle Extremal graph Extremal graph Generalized Tur & aacute;n number Generalized Tur & aacute;n number
Cite：
Copy from the list or Export to your reference management。
| GB/T 7714 | Hou, Jianfeng , Yang, Caihong , Zeng, Qinghou . Counting triangles in graphs without vertex disjoint odd cycles [J]. | DISCRETE MATHEMATICS , 2024 , 347 (7) . |
| MLA | Hou, Jianfeng et al. "Counting triangles in graphs without vertex disjoint odd cycles" . | DISCRETE MATHEMATICS 347 . 7 (2024) . |
| APA | Hou, Jianfeng , Yang, Caihong , Zeng, Qinghou . Counting triangles in graphs without vertex disjoint odd cycles . | DISCRETE MATHEMATICS , 2024 , 347 (7) . |
| Export to | NoteExpress RIS BibTex |
Version ：
Abstract ：
不同于图的情形,对于正整数r≥3和一些经典的r-一致超图族M,顶点数固定条件下边数最多的不含M的r-一致超图(称为M的极图)可能不止一个,而且这些超图在距离上相距较远,这种现象被称为不稳定性,也是确定此类超图Turán数的基本障碍. Liu和Mubayi (2022)给出了第一个具有不稳定性的3-一致超图族的例子.对于r≥4,通过具有不稳定性的3-一致超图族可以构造具有同样性质的r-一致超图族.本文构造第一个不依赖于3-一致超图的4-一致超图族M,使得M有两个在距离上相距较远的极图.同时,本文证明相应的Andrásfai-Erd?os-Sós型稳定性定理:任意最小度接近于极图平均度的不含M的4-一致超图一定是这两个极图中一个的子图.此外,作为本文结果的推论,本文还证明了M的可行域具有两个最大值点.
Keyword ：
Turán数 Turán数 可行域 可行域 稳定性 稳定性 超图 超图
Cite：
Copy from the list or Export to your reference management。
| GB/T 7714 | 张一枭 , 李恒 , 侯建锋 . 不具有稳定性质的4-一致超图族 献给刘桂真教授80寿辰 [J]. | 中国科学:数学 , 2024 , 54 (11) : 1905-1924 . |
| MLA | 张一枭 et al. "不具有稳定性质的4-一致超图族 献给刘桂真教授80寿辰" . | 中国科学:数学 54 . 11 (2024) : 1905-1924 . |
| APA | 张一枭 , 李恒 , 侯建锋 . 不具有稳定性质的4-一致超图族 献给刘桂真教授80寿辰 . | 中国科学:数学 , 2024 , 54 (11) , 1905-1924 . |
| Export to | NoteExpress RIS BibTex |
Version ：
Abstract ：
The Turan number of a graph H, denoted by ex(n, H), is the maximum number of edges in an n-vertex graph that does not contain H as a subgraph. For a vertex v and a multi-set F of graphs, the suspension F + v of F is the graph obtained by connecting the vertex v to all vertices of F for each F is an element of F. For two integers k 1 and r 2, let Hi be a graph containing a critical edge with chromatic number r for any i is an element of {1, ... , k}, and let H = {H1,. . . , Hk} + v. In this paper, we determine ex(n, H) and characterize all the extremal graphs for sufficiently large n. This generalizes a result of Chen, Gould, Pfender and Wei on intersecting cliques.
Cite：
Copy from the list or Export to your reference management。
| GB/T 7714 | Hou, Jianfeng , Li, Heng , Zeng, Qinghou . Extremal Graphs for the Suspension of Edge-Critical Graphs [J]. | ELECTRONIC JOURNAL OF COMBINATORICS , 2024 , 20 (4) . |
| MLA | Hou, Jianfeng et al. "Extremal Graphs for the Suspension of Edge-Critical Graphs" . | ELECTRONIC JOURNAL OF COMBINATORICS 20 . 4 (2024) . |
| APA | Hou, Jianfeng , Li, Heng , Zeng, Qinghou . Extremal Graphs for the Suspension of Edge-Critical Graphs . | ELECTRONIC JOURNAL OF COMBINATORICS , 2024 , 20 (4) . |
| Export to | NoteExpress RIS BibTex |
Version ：
Abstract ：
Let r >= 2 be an integer. The real number alpha is an element of [0, 1) is a jump for r if there exists a constant c > 0 such that for any & varepsilon; > 0 and any integer m >= r, there exists an integer n(0)(& varepsilon;, m) satisfying any r-uniform graph with n >= n(0) (& varepsilon;, m) vertices and density at least alpha + & varepsilon; contains a subgraph with m vertices and density at least alpha + c. A result of Erdos and Simonovits (1966) and Erdos and Stone (1946) implies that every alpha is an element of [0, 1) is a jump for r = 2. Erdos (1964) asked whether the same is true for r >= 3. Frankl and Rodl (1984) gave a negative answer by showing that 1-1/& ell;(r-1) is not a jump for r if r >= 3 and & ell; > 2r. After that, more non-jumps are found by using a method of Frankl and Rodl (1984). Motivated by an idea of Liu and Pikhurko (2023), in this paper, we show a method to construct maps f: [0, 1) -> [0, 1) that preserve non-jumps, i.e., if alpha is a non-jump for r given by the method of Frankl and Rodl (1984), then f(alpha) is also a non-jump for r. We use these maps to study hypergraph Turan densities and answer a question posed by Grosu (2016).
Keyword ：
hypergraph Lagrangian hypergraph Lagrangian jumping number jumping number non-jump non-jump Turan density Turan density
Cite：
Copy from the list or Export to your reference management。
| GB/T 7714 | Hou, Jianfeng , Li, Heng , Yang, Caihong et al. Generating non-jumps from a known one [J]. | SCIENCE CHINA-MATHEMATICS , 2024 , 67 (12) : 2899-2908 . |
| MLA | Hou, Jianfeng et al. "Generating non-jumps from a known one" . | SCIENCE CHINA-MATHEMATICS 67 . 12 (2024) : 2899-2908 . |
| APA | Hou, Jianfeng , Li, Heng , Yang, Caihong , Zhang, Yixiao . Generating non-jumps from a known one . | SCIENCE CHINA-MATHEMATICS , 2024 , 67 (12) , 2899-2908 . |
| Export to | NoteExpress RIS BibTex |
Version ：
Abstract ：
We give the first exact and stability results for a hypergraph Turan problem with infinitely many extremal constructions that are far from each other in edit-distance. This includes an example of triple systems with Turan density 2/9, thus answering some questions posed by the third and fourth authors and Reiher about the feasible region of hypergraphs. Our results also provide extremal constructions whose shadow density is a transcendental number. Our novel approach is to construct certain multilinear polynomials that attain their maximum (in the standard simplex) on a line segment and then to use these polynomials to define an operation on hypergraphs that gives extremal constructions.
Keyword ：
feasible region feasible region Hypergraph Turan problem Hypergraph Turan problem Lagrangian Lagrangian multilinear polynomials multilinear polynomials nonminimal hypergraphs nonminimal hypergraphs shadow shadow stability stability
Cite：
Copy from the list or Export to your reference management。
| GB/T 7714 | Hou, Jianfeng , Li, Heng , Liu, Xizhi et al. Hypergraphs with Infinitely Many Extremal Constructions [J]. | DISCRETE ANALYSIS , 2023 . |
| MLA | Hou, Jianfeng et al. "Hypergraphs with Infinitely Many Extremal Constructions" . | DISCRETE ANALYSIS (2023) . |
| APA | Hou, Jianfeng , Li, Heng , Liu, Xizhi , Mubayi, Dhruv , Zhang, Yixiao . Hypergraphs with Infinitely Many Extremal Constructions . | DISCRETE ANALYSIS , 2023 . |
| Export to | NoteExpress RIS BibTex |
Version ：
Abstract ：
For a graph G and two positive integers t, r, a (t, t + r)-list assignment of G is a function L that assigns a set of permissible colors L(u) to every vertex u such that |L(u) | >= t and |L(u) u L(w) | >= t + r when uw is an edge. The graph G is said to be (t, t + r)-choosable if G allows a proper coloring psi satisfying psi (u) E L(u) for each u E V (G ) and each (t, t + r)-list assignment L of G . In this paper, we consider the (2, 2 + r)-choosability of planar graphs without short cycles. We show that: (1) if G is a planar graph contains no cycles of length 4, then G is (2,9)-choosable; (2) if G is a planar graph contains no cycles of lengths 4 and 5, then G is (2,7)-choosable.(c) 2022 Elsevier Inc. All rights reserved.
Keyword ：
Choosability Choosability C k-free C k-free Discharging Discharging Planar graphs Planar graphs
Cite：
Copy from the list or Export to your reference management。
| GB/T 7714 | Hou, Jianfeng , Zhu, Hongguo . On (2, r)-choosability of planar graphs without short cycles [J]. | APPLIED MATHEMATICS AND COMPUTATION , 2023 , 444 . |
| MLA | Hou, Jianfeng et al. "On (2, r)-choosability of planar graphs without short cycles" . | APPLIED MATHEMATICS AND COMPUTATION 444 (2023) . |
| APA | Hou, Jianfeng , Zhu, Hongguo . On (2, r)-choosability of planar graphs without short cycles . | APPLIED MATHEMATICS AND COMPUTATION , 2023 , 444 . |
| Export to | NoteExpress RIS BibTex |
Version ：
Export
| Results： |
Selected to |
| Format： |
