保距序图的运算性质
Operational properties of sequentially distance preserving graphs
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摘要: 在组合交换代数等问题的研究中, 尤其是在单纯复形的图论刻画中, 保距序图都有着广泛的应用, 并逐渐成为解决相关问题的关键。针对保距序图, 以连接和粘合等图操作为技术手段, 着重刻画了保距性质在一些特定的图运算之下是否保持。具体地, 结合数学归纳法与图连接运算的保距性分析, 证明了任意2个图的连接图都是保距序图。同时, 结合保距子图与图粘合运算的保距性分析, 揭示了2个图粘合后保持保距序性的充分必要条件, 即当且仅当此2个图都是保距序图, 且至少其中1个图的保距序的最后1个顶点为粘合点。 研究过程中建立了基于图的结构分析与归纳推理的技术路线, 为保距序图的整体刻画提供了理论基础, 为单纯复形的图论刻画提供了技术手段。Abstract: In the study of combinatorial commutative algebra, especially in the graph-theoretic characterization of simplicial complexes, sequentially distance preserving graphs are widely used and play the important role in solving the corresponding problems. In the report, aimed at sequentially distance preserving graphs, the graph operations including connection and union were used as the main methods to characterize whether the sequentially distance preserving property is kept under the corresponding graph operations. Specifically, the mathematical induction and the detailed analysis on the distance preserving property under graph connection were integrated to prove that the connection graph of any two graphs remains sequentially distance preserving. The analyses for distance preserving subgraphs and the distance preserving property under graph union were used to propose an equivalent condition for maintaining the sequentially distance preserving property after union, a union graph is sequentially distance preserving if and only if both original graphs are sequentially distance preserving, and for at least one of them, the terminal vertex of its distance preserving sequence is the common vertex of the two original graphs. During the research process, the technical roadmap based on graph structure analysis and inductive reasoning was established, which provides the theoretical basis for the complete characterization of sequentially distance preserving graphs and the technical method for the graph-theoretic characterization of simplicial complexes.