Suda （2012） extended the ErdSs-Ko-Rado theorem to designs in strongly regularized semilattices. In this paper we generalize Suda＇s results in regularized semilattices and partition regularized semilattices, give ma...Suda （2012） extended the ErdSs-Ko-Rado theorem to designs in strongly regularized semilattices. In this paper we generalize Suda＇s results in regularized semilattices and partition regularized semilattices, give many examples for these semilattices and obtain their intersection theorems.展开更多
For a graph G and an integer r ≥ 1, G is r-EKR if no intersecting family of independent r-sets of G is larger than the largest star （a family of independent r-sets containing some fixed vertex in G）, and G is stric...For a graph G and an integer r ≥ 1, G is r-EKR if no intersecting family of independent r-sets of G is larger than the largest star （a family of independent r-sets containing some fixed vertex in G）, and G is strictly r-EKR if every extremal intersecting family of independent r-sets is a star. Recently, Hurlbert and Kamat gave a preliminary result about EKR property of ladder graphs. They showed that a ladder graph with n rungs is 3-EKR for all n ≥3. The present paper proves that this graph is r-EKR for all 1 ≤ r 〈 n, and strictly r-EKR except for r = n - 1.展开更多
For k = （k1,...,kn） E Nn, 1 ≤ k1 ≤ ... ≤ kn, let Lkr be the family of labeled r-sets on k given by Lkr：= {{（a1,la1）,...,（ar,lar）} ： {a1,...,ar} [n],lai ∈ [kai],i = 1,...,r}. A family A of labeled r-sets i...For k = （k1,...,kn） E Nn, 1 ≤ k1 ≤ ... ≤ kn, let Lkr be the family of labeled r-sets on k given by Lkr：= {{（a1,la1）,...,（ar,lar）} ： {a1,...,ar} [n],lai ∈ [kai],i = 1,...,r}. A family A of labeled r-sets is intersecting if any two sets in ~4 intersect. In this paper we give the sizes and structures of intersecting families of labeled r-sets.展开更多
基金supported by National Natural Science Foundation of China(Grant Nos.11271047 and 10971052)Natural Science Foundation of Hebei Province(Grant Nos.A2012408003 and A2012205079)+3 种基金the Talent Project Fund of Hebei Province(Grant No.2011-11)the Doctoral Fund from Hebei Normal University(Grant No.L2011B02)Scientific Research Fund of the Department of Education of Hebei Education Department(Grant No.ZH2012082)the Fundamental Research Funds for the Central University of China
文摘Suda （2012） extended the ErdSs-Ko-Rado theorem to designs in strongly regularized semilattices. In this paper we generalize Suda＇s results in regularized semilattices and partition regularized semilattices, give many examples for these semilattices and obtain their intersection theorems.
基金Supported by the National Natural Science Foundation of China(No.11201409,No.11371327)the Natural Science Foundation of Hebei Province of China(No.A2013203009)
文摘For a graph G and an integer r ≥ 1, G is r-EKR if no intersecting family of independent r-sets of G is larger than the largest star （a family of independent r-sets containing some fixed vertex in G）, and G is strictly r-EKR if every extremal intersecting family of independent r-sets is a star. Recently, Hurlbert and Kamat gave a preliminary result about EKR property of ladder graphs. They showed that a ladder graph with n rungs is 3-EKR for all n ≥3. The present paper proves that this graph is r-EKR for all 1 ≤ r 〈 n, and strictly r-EKR except for r = n - 1.
基金Supported by the National Natural Science Foundation of China (No. 11001249)the Mathematical Tianyuan Foundation of China (No. 11026180)
文摘For k = （k1,...,kn） E Nn, 1 ≤ k1 ≤ ... ≤ kn, let Lkr be the family of labeled r-sets on k given by Lkr：= {{（a1,la1）,...,（ar,lar）} ： {a1,...,ar} [n],lai ∈ [kai],i = 1,...,r}. A family A of labeled r-sets is intersecting if any two sets in ~4 intersect. In this paper we give the sizes and structures of intersecting families of labeled r-sets.
