共查询到20条相似文献，搜索用时 31 毫秒
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This paper is concerned with the enumeration of a special kind of labeled connected graphs of whichhe cutpoint-graphs are trees. A new method-treelization is introduced, by which the enumeration of this special kind of graphs can be solved. The enumerative formula with generating function is derived. The method of treelization is powerful in solving enumeration problems of graphs and deserves further research. For example,using the similar way, another special kind of labeled connected graphs of which the block-graphs are trees can be enumerated. 相似文献
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杨峰 《西安文理学院学报》2011,14(1):64-66
介绍了一种Wiener指标的计算方法,主要是通过建立简单连通图的层结构进行Wiener指标的计算,并利用层结构等价关系计算了一类类似K方体图的Wiener指标.通过所介绍的方法,还可以计算一些规则图,特别是以每一点为对称中心图的Wiener指标. 相似文献
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王文霞 《雁北师范学院学报》2014,(2):10-13
同构图指的是在两个图中寻找顶点之间对应的映射,通过映射使得两图中的各条边也保持对应的关系。为了有效提高寻找有向同构图的时间效率、简化操作,首先研究了有向图同构的矩阵存储方式,并针对性的提出了用出入度序列来判断有向图的同构算法。与矩阵存储算法相比,该判定算法的时间更为简短。通过执行判定过程验证了算法的正确性。 相似文献
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张冰 《广东技术师范学院学报》2008,(6)
一个连通图的维纳指数W(G)等于图中所有无序点对的距离之和。本文研究了连通图和不连通图的维纳指数W(G),得到了上界图;以及研究了W(G) W(G)的上界和下界。 相似文献
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Inquiry instruction often neglects graphing. It gives students few opportunities to develop the knowledge and skills necessary to take advantage of graphs, and which are called for by current science education standards. Yet, it is not well known how to support graphing skills, particularly within middle school science inquiry contexts. Using qualitative graphs is a promising, but underexplored approach. In contrast to quantitative graphs, which can lead students to focus too narrowly on the mechanics of plotting points, qualitative graphs can encourage students to relate graphical representations to their conceptual meaning. Guided by the Knowledge Integration framework, which recognizes and guides students in integrating their diverse ideas about science, we incorporated qualitative graphing activities into a seventh grade web-based inquiry unit about cell division and cancer treatment. In Study 1, we characterized the kinds of graphs students generated in terms of their integration of graphical and scientific knowledge. We also found that students (n = 30) using the unit made significant learning gains based on their pretest to post-test scores. In Study 2, we compared students' performance in two versions of the same unit: One that had students construct, and second that had them critique qualitative graphs. Results showed that both activities had distinct benefits, and improved students' (n = 117) integrated understanding of graphs and science. Specifically, critiquing graphs helped students improve their scientific explanations within the unit, while constructing graphs led students to link key science ideas within both their in-unit and post-unit explanations. We discuss the relative affordances and constraints of critique and construction activities, and observe students' common misunderstandings of graphs. In all, this study offers a critical exploration of how to design instruction that simultaneously supports students' science and graph understanding within complex inquiry contexts. 相似文献
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Wu Qing Hao 《广东技术师范学院学报》1993,(4)
本文给出一个搜索满足G~3=G的循环图的算法,并搜索到满足G~3=G的2度循环图只有C_9<1>一个图,而满足G~3=G的4度循环图共有三个图:C_(27)<1,5>,C_(27)<1,11>和C_(18)<1,8>。 相似文献
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Polysemy in graph-related practices is the phenomenon that a single graph can sustain different meanings assigned to it. Considerable research has been done on polysemy in graph-related practices in school science in which graphs are rather used as scientific tools. However, graphs in science textbooks are also used rather pedagogically to illustrate domain-specific textbook content and less empirical work has been done in this respect. The aim of this study is therefore to better understand polysemy in the domain-specific pedagogical use of graphs in science textbooks. From socio-cultural and cultural-historical perspectives, we perceive polysemy as irreducible to either the meaning-making (semiotic) resources provided by the graph or its readers who assign meaning to it. Departing from this framework, we simultaneously investigated: (a) the meanings 44 pre-university biology students assigned to the Cartesian plane of a graph that is commonly used as a pedagogical tool in Dutch high school biology textbooks (an electrocardiogram); (b) the semiotic resources provided by this graph; and (c) the educational practices of which it is supposedly a part according to the actions constituted by the textbooks that were to be conducted by students. Drawing on this case, we show polysemy in the pedagogical use of graphs in science textbooks. In turn, we show how this polysemy can be explained dialectically as the result of both the meaning-making resources provided by the textbooks and the graph-related practices in which students supposedly engaged by using their textbooks. The educational implications of these findings are discussed. 相似文献
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Padmakar-Ivan（PI）指数是一个类似于Wiener指数的拓扑指数,它能够反应有机分子的某些结构特征。给出给定顶点数和叶子节点数的Halin图的PI指数,并刻画具有相应PI指数的Halin图类。 相似文献
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袁静 《安阳师范学院学报》2014,(5):4-7
称图Γ是弧传递图,如果Γ的自同构群AutΓ作用在其弧集上传递.在valΓ≥3的情形下,本文给出了S5的连通弧传递陪集图的一个完全分类.证明了在同构意义下,这样的图有18个:2个3度弧传递图;7个4度弧传递图;3个5度弧传递图;5个6度弧传递图;1个8度弧传递图. 相似文献
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图的包装是一重要的图论概念并有着多方面的应用,本文用矩阵方法讨论图的包装问题,得到了两个同阶图可包装的充要条件. 相似文献
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利用伴随多项式的性质,多项式的整除性,特征标,最小伴随实根,刻画了图Bn∪Dm（m≥5）的伴随等价图。 相似文献
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Maj-Britt Isberner Tobias Richter Johanna Maier Katja Knuth-Herzig Holger Horz Wolfgang Schnotz 《Instructional Science》2013,41(5):849-872
When reading conflicting science-related texts, readers may attend to cues which allow them to assess plausibility. One such plausibility cue is the use of graphs in the texts, which are regarded as typical of ‘hard science’. The goal of our study was to investigate the effects of the presence of graphs on the perceived plausibility and situation model strength for conflicting science-related texts, while including the influence of readers’ amount of experience with scientific texts and graphs as a potential moderator of these effects. In an experiment mimicking web-based informal learning, 77 university students read texts on controversial scientific issues which were presented with either graphs or tables. Perceived plausibility and situation model strength for each text were assessed immediately after reading; reader variables were assessed several weeks prior to the experiment proper. The results suggest that graphs can indeed serve as plausibility cues and thus boost situation model strength for texts which contain them. This effect was mediated by the perceived plausibility of the information in the texts with graphs. However, whether readers use graphs as plausibility cues in texts with conflicting information seems to depend also on their amount of experience with scientific texts and graphs. 相似文献
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Danri H. Delport 《Teaching Statistics》2021,43(1):36-43
It is said that a picture is worth a thousand words, but what about graphs? Although graphs have the potential to bring data to life, numerous studies show that learners struggle with graphical comprehension. Furthermore, many textbook examples on graphs are boring and appear meaningless to students. Students want to know more about something which is interesting, meaningful, and worth knowing, in other words, something relevant. With the outbreak of the novel coronavirus in December 2019, COVID‐19 is dominating the news worldwide, and the internet is flooded with visual presentations about the virus. To make statistics more fascinating and exciting, relevant and real‐world data such as these can be used in the classroom to stimulate the learning of important statistical concepts such as graphs. Curcio's three levels of graphical comprehension were used as a framework in this study, while the importance of developing a global view on distributions was also emphasized. 相似文献
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Our study integrates automated natural language-oriented assessment and analysis methodologies into feasible reading comprehension
tasks. With the newly developed T-MITOCAR toolset, prose text can be automatically converted into an association net which
has similarities to a concept map. The “text to graph” feature of the software is based on several parsing heuristics and
can be used both to assess the learner’s understanding by generating graphical information from his or her text and to generate
conceptual graphs from text which can be used as learning materials. In this study we investigate the effects of association
nets made available to learners prior to reading. The results reveal that the automatically created graphs are highly similar
to classical expert graphs. However, neither the association nets nor the expert graphs had a significant effect on learning,
although the latter have been reported to have an effect in previous studies. 相似文献
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This paper presents a conceptual analysis for students’ images of graphs and their extension to graphs of two-variable functions. We use the conceptual analysis, based on quantitative and covariational reasoning, to construct a hypothetical learning trajectory (HLT) for how students might generalize their understanding of graphs of one-variable functions to graphs of two-variable functions. To evaluate the viability of this learning trajectory, we use data from two teaching experiments based on tasks intended to support development of the schemes in the HLT. We focus on the schemes that two students developed in these teaching experiments and discuss their relationship to the original HLT. We close by considering the role of covariational reasoning in generalization, consider other ways in which students might come to conceptualize graphs of two-variable functions, and discuss implications for instruction. 相似文献