87 research outputs found
Hypergraphs Do Jump
No full textWe say that α ∈ [0, 1) is a jump for an integer r ≥ 2 if there exists c(α) > 0 such that for all ϵ > 0 and all t ≥ 1, any r-graph with n ≥ n0(α, ϵ, t) vertices and density at least α + ϵ contains a subgraph on t vertices of density at least α + c.The Erdős–Stone–Simonovits theorem [4, 5] implies that for r = 2, every α ∈ [0, 1) is a jump. Erdős [3] showed that for all r ≥ 3, every α ∈ [0, r!/rr) is a jump. Moreover he made his famous ‘jumping constant conjecture’, that for all r ≥ 3, every α ∈ [0, 1) is a jump. Frankl and Rödl [7] disproved this conjecture by giving a sequence of values of non-jumps for all r ≥ 3.We use Razborov's flag algebra method [9] to show that jumps exist for r = 3 in the interval [2/9, 1). These are the first examples of jumps for any r ≥ 3 in the interval [r!/rr, 1). To be precise, we show that for r = 3 every α ∈ [0.2299, 0.2316) is a jump.We also give an improved upper bound for the Turán density of K4− = {123, 124, 134}: π(K4−) ≤ 0.2871. This in turn implies that for r = 3 every α ∈ [0.2871, 8/27) is a jump.</jats:p
Exploring Emerging Business Model Value Chains in New Space
Get PDFOver the past twenty years, business activities related to opportunities provided by New Space have undergone constant change. These changes challenge existing business models and value chains. In this work, we discuss these changes based on the literature, expert interviews, and case examples from the industry. We demonstrate eight different value chains in New Space business. These include conventional value chains as well novel ones, all in the context of space business. The value chains investigated are at different levels of abstraction and include data, hardware, intellectual property, prestige, mission planning, tourism, and space services. The eighth value chain is an aggregated overview of the whole of New Space business. Furthermore, we discuss business opportunities within these value chains and provide insights into totally new business model value chains that are emerging in New Space. Lastly, we consider feedback loops in the value chains of New Space that should be understood by academic researchers and business managers.© The Author(s) 2024. This chapter is licensed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.
The images or other third party material in this chapter are included in the chapter's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the chapter's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.fi=vertaisarvioitu|en=peerReviewed
New Space Era : Characteristics of the New Space Industry Landscape
Get PDFIn recent decades, the space industry has undergone enormous changes, transitioning from government-led space projects (referred to as “old space”) toward a more entrepreneurial and commercial utilization of space by private firms (termed “new space”). Due to these rapid changes, there is a pressing need for up-to-date insights into the field, encompassing its theories and characteristics, particularly concerning business activities related to space. In this chapter, we present five propositions for further study and more detailed investigation. These propositions are based on current literature and qualitative data gathered from 10 experts working in key roles within the space industry. Finally, the chapter identifies key theoretical elements that help elucidate how the space business is evolving and its likely trajectory in the near future.©The Author(s) 2024. This chapter is licensed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.
The images or other third party material in this chapter are included in the chapter's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the chapter's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.fi=vertaisarvioitu|en=peerReviewed
Graph Guessing Games and Non-Shannon Information Inequalities
Get PDFGuessing games for directed graphs were introduced by Riis [12] for studying multiple unicast network coding problems. In a guessing game, the players toss generalised dice and can see some of the other outcomes depending on the structure of an underlying digraph. They later guess simultaneously the outcome of their own die. Their objective is to find a strategy which maximises the probability that they all guess correctly. The performance of the optimal strategy for a graph is measured by the guessing number of the digraph.
In [3], Christofides and Markstrom studied guessing numbers of undirected graphs and defined a strategy which they conjectured to be optimal. One of the main results of this paper is a disproof of this conjecture.
The main tool so far for computing guessing numbers of graphs is information theoretic inequalities. The other main result of the paper is that Shannon's information inequalities, which work particularly well for a wide range of graph classes, are not sufficient for computing the guessing number.
Finally we pose a few more interesting questions some of which we can answer and some which we leave as open problems
The minimal density of triangles in tripartite graphs
No full textAbstractWe determine the minimal density of triangles in a tripartite graph with prescribed edge densities. This extends a previous result of Bondy, Shen, Thomassé and Thomassen characterizing those edge densities guaranteeing the existence of a triangle in a tripartite graph. To be precise we show that a suitably weighted copy of the graph formed by deleting a certain 9-cycle fromK3,3,3has minimal triangle density among all weighted tripartite graphs with prescribed edge densities.Supplementary materials are available with this article.</jats:p
Some of the social welfare organizations in Colorado
Get PDFJune 16, 1929.Includes bibliographical references (pages 93-99)
Cause of low COVID 19 detection and mortality rate in Pakistan and India
No full textThe COVID 19 has become a concern for all the countries of the world. More than 276,000 and 4 million people have been killed and infected, respectively. The author wants to emphasize the reasons of low COVID 19 detection and mortality rate in both Pakistan and India
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The British judges of the International Court of Justice ::an explication? the later jurists /
No full text"The monograph considers the individual and joint dissertations, separate opinions and dissenting opinions that British judges Sir Gerald Fitzmaurice, Sir Humphrey Waldock, Sir Robert Jennings, Dame Rosalyn Higgins and Sir Christopher Greenwood appended to Judgments and Advisory Opinions of the International Court of Justice. It provides information of the life of, and reviews some of the scholarship of, these judges. In the final chapter, the author endeavours to identify characteristics of the British judges of the International Court of Justice that are shared by some of all of these five jurists - together with their predecessors at the Court, Baron Arnold McNair and Sir Hersch Lauterpacht"-
Is utility in the mind of the beholder? A review of ergonomics methods
No full textThis paper reviews the use of ergonomics methods in the context of usability of consumer products. A review of the literature indicated that there is upward of 60 methods available to the ergonomist. The results of the survey indicated that questionnaires, interviews and observation are the most frequently reported methods used. Ease of use of the methods was dependent upon type of method used, presence of software support and type of training received. Strong links were found between questionnaires and interviews as a combined approach, as well as with HTA and observation. However, a questionnaire survey of professional ergonomists found that none of the respondents had any documented evidence of the reliability and validity of the methods they were using. A study of training people to use ergonomics' methods indicated the different requirements of the approaches, in terms of training time, application time and subjective preferences. An important goal for future research is to establish the reliability and validity of ergonomics methods
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