{"title":"Über die Nichtexistenz zweier Knotenpunkte eines Graphen, die alle längsten Kreise fassen","authors":"Hansjoachim Walther","doi":"10.1016/S0021-9800(70)80085-0","DOIUrl":"10.1016/S0021-9800(70)80085-0","url":null,"abstract":"<div><p>Es wird ein zweifach zusammenhängender (nichtplanarer) Graph angegeben, der keine zwei Knotenpunkte besitzt, so daß jeder längste Kreis des Graphen durch weinigstens einen der beiden Knotenpunkte geht.</p></div>","PeriodicalId":100765,"journal":{"name":"Journal of Combinatorial Theory","volume":"8 3","pages":"Pages 330-333"},"PeriodicalIF":0.0,"publicationDate":"1970-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0021-9800(70)80085-0","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86077497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A combinatorial proof of Tucker's lemma for the n-cube","authors":"James K. Baker","doi":"10.1016/S0021-9800(70)80081-3","DOIUrl":"10.1016/S0021-9800(70)80081-3","url":null,"abstract":"<div><p>Tucker's lemma is a combinatorial result which may be used to derive several theorems in topology. Some basic properties are established for the cube of integer lattice points. Tucker's lemma is then proved by applying a result which was originally presented for the octahedral subdivision of the <em>n</em>-disk.</p></div>","PeriodicalId":100765,"journal":{"name":"Journal of Combinatorial Theory","volume":"8 3","pages":"Pages 279-290"},"PeriodicalIF":0.0,"publicationDate":"1970-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0021-9800(70)80081-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88489534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Higher-Dimensional analogs of the four-color problem and some inequalities for simplicial complexes","authors":"Branko Grünbaum","doi":"10.1016/S0021-9800(70)80071-0","DOIUrl":"10.1016/S0021-9800(70)80071-0","url":null,"abstract":"<div><p>Abstract</p><p>The four-color problem concerning planar graphs is shown to have meaningful higher-dimensional analogs.</p></div>","PeriodicalId":100765,"journal":{"name":"Journal of Combinatorial Theory","volume":"8 2","pages":"Pages 147-153"},"PeriodicalIF":0.0,"publicationDate":"1970-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0021-9800(70)80071-0","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91156195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The heawood map-coloring problem—Cases 1, 7, and 10","authors":"J.W.T. Youngs","doi":"10.1016/S0021-9800(70)80076-X","DOIUrl":"10.1016/S0021-9800(70)80076-X","url":null,"abstract":"<div><p>This paper gives a proof of the fact that the chromatic number of an orientable surface of genus <em>p</em> is equal to the integral part of <span><math><mrow><mrow><mrow><mrow><mo>(</mo><mrow><mn>7</mn><mo>+</mo><msqrt><mrow><mn>1</mn><mo>+</mo><mn>48</mn><mi>p</mi></mrow></msqrt></mrow><mo>)</mo></mrow></mrow><mo>/</mo><mn>2</mn></mrow></mrow></math></span> whenever the latter is congruent to 1, 7 or 10 modulo 12.</p></div>","PeriodicalId":100765,"journal":{"name":"Journal of Combinatorial Theory","volume":"8 2","pages":"Pages 220-231"},"PeriodicalIF":0.0,"publicationDate":"1970-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0021-9800(70)80076-X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85550555","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The achromatic number of a graph","authors":"Frnak Harary , Stephen Hedetniemi","doi":"10.1016/S0021-9800(70)80072-2","DOIUrl":"10.1016/S0021-9800(70)80072-2","url":null,"abstract":"<div><p>The concept of coloring a graph has been shown to be subsumed by that of an homomorphism. This led in [3] to the definition of a complete <em>n</em>-coloring of a graph <em>G</em> and suggested therefore a new invariant, which we now call the “achromatic number” <em>ψ(G)</em>. While the chromatic number <em>χ(G)</em> is the minimum number of colors required for (a complete coloring of) the points of <em>G</em>, the achromatic number is the maximum such number. We obtain several bounds for <em>ψ(G)</em> in terms of other invariants of a graph, and in particular we show that, for any graph <em>G</em> having <em>p</em> points, <em><sub>x</sub>(G)+ͨ(G)¯⩽p+1</em>, a result which generalizes a theorem of Nordhaus and Gaddum [4].</p></div>","PeriodicalId":100765,"journal":{"name":"Journal of Combinatorial Theory","volume":"8 2","pages":"Pages 154-161"},"PeriodicalIF":0.0,"publicationDate":"1970-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0021-9800(70)80072-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79268225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Solution of the heawood map-coloring problem—Case 4","authors":"C.M. Terry, L.R. Welch, J.W.T. Youngs","doi":"10.1016/S0021-9800(70)80074-6","DOIUrl":"10.1016/S0021-9800(70)80074-6","url":null,"abstract":"<div><p>This paper gives a proof of the fact that the chromatic number of an orientable surface of genus <em>p</em> is equal to the integral part of <span><math><mrow><mrow><mrow><mrow><mo>(</mo><mrow><mn>7</mn><mo>+</mo><msqrt><mrow><mn>1</mn><mo>+</mo><mn>48</mn><mi>p</mi></mrow></msqrt></mrow><mo>)</mo></mrow></mrow><mo>/</mo><mn>2</mn></mrow></mrow></math></span> whenever the latter is congruent to 4 modulo 12.</p></div>","PeriodicalId":100765,"journal":{"name":"Journal of Combinatorial Theory","volume":"8 2","pages":"Pages 170-174"},"PeriodicalIF":0.0,"publicationDate":"1970-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0021-9800(70)80074-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86329173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Solution of the heawood map-coloring problem—Cases 3, 5, 6, and 9","authors":"J.W.T. Youngs","doi":"10.1016/S0021-9800(70)80075-8","DOIUrl":"10.1016/S0021-9800(70)80075-8","url":null,"abstract":"<div><p>This paper gives a proof of the fact that the chromatic number of an orientable surface of genus <em>p</em> is equal to the integral part of <span><math><mrow><mrow><mrow><mrow><mo>(</mo><mrow><mn>7</mn><mo>+</mo><msqrt><mrow><mn>1</mn><mo>+</mo><mn>48</mn><mi>p</mi></mrow></msqrt></mrow><mo>)</mo></mrow></mrow><mo>/</mo><mn>2</mn></mrow></mrow></math></span> whenever the latter is congruent to 3, 5, 6, or 9 modulo 12.</p></div>","PeriodicalId":100765,"journal":{"name":"Journal of Combinatorial Theory","volume":"8 2","pages":"Pages 175-219"},"PeriodicalIF":0.0,"publicationDate":"1970-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0021-9800(70)80075-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85623308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A procedure for dissecting a rectangle into squares, and an example for the rectangle whose sides are in the ratio 2:1","authors":"R.L. Brooks","doi":"10.1016/S0021-9800(70)80077-1","DOIUrl":"https://doi.org/10.1016/S0021-9800(70)80077-1","url":null,"abstract":"","PeriodicalId":100765,"journal":{"name":"Journal of Combinatorial Theory","volume":"8 2","pages":"Pages 232-243"},"PeriodicalIF":0.0,"publicationDate":"1970-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0021-9800(70)80077-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91683221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Operator theoretic invariants and the enumeration theory of Pólya and de Bruijn","authors":"S.G. Williamson","doi":"10.1016/S0021-9800(70)80073-4","DOIUrl":"10.1016/S0021-9800(70)80073-4","url":null,"abstract":"<div><p>It has been shown by M. Marcus and others that, in regard to combinatorial matrix functions and combinatorial inequalities, it is frequently fruitful to pass immediately from the consideration of permutations to the consideration of their tensor representations. Such an approach embeds the combinatorial arguments into the framework of linear algebra and frequently results in deeper theorems. It is interesting to note that certain basic combinatorial identities concerned with pattern enumeration and combinatorial generating functions can also be put into this framework. In this paper we consider one possible way of doing this.</p></div>","PeriodicalId":100765,"journal":{"name":"Journal of Combinatorial Theory","volume":"8 2","pages":"Pages 162-169"},"PeriodicalIF":0.0,"publicationDate":"1970-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0021-9800(70)80073-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88572263","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}