{ "id": "1910.05058", "version": "v1", "published": "2019-10-11T10:00:34.000Z", "updated": "2019-10-11T10:00:34.000Z", "title": "Spanning Triangle-trees and Flows of Graphs", "authors": [ "Jiaao Li", "Xueliang Li", "Meiling Wang" ], "comment": "16 pages, 8 figures", "categories": [ "math.CO" ], "abstract": "In this paper we study the flow-property of graphs containing a spanning triangle-tree. Our main results provide a structure characterization of graphs with a spanning triangle-tree admitting a nowhere-zero $3$-flow. All these graphs without nowhere-zero $3$-flows are constructed from $K_4$ by a so-called bull-growing operation. This generalizes a result of Fan et al. in 2008 on triangularly-connected graphs and particularly shows that every $4$-edge-connected graph with a spanning triangle-tree has a nowhere-zero $3$-flow. A well-known classical theorem of Jaeger in 1979 shows that every graph with two edge-disjoint spanning trees admits a nowhere-zero $4$-flow. We prove that every graph with two edge-disjoint spanning triangle-trees has a flow strictly less than $3$.", "revisions": [ { "version": "v1", "updated": "2019-10-11T10:00:34.000Z" } ], "analyses": { "subjects": [ "05C21", "05C40", "05C05" ], "keywords": [ "nowhere-zero", "edge-disjoint spanning trees admits", "main results", "structure characterization", "edge-disjoint spanning triangle-trees" ], "note": { "typesetting": "TeX", "pages": 16, "language": "en", "license": "arXiv", "status": "editable" } } }