1,444 research outputs found
Some progress on the existence of 1-rotational Steiner Triple Systems
No full textA Steiner Triple System of order v (briefly STS(v)) is 1-rotational under G if it admits G as an automorphism group acting sharply transitively on all but one point.The spectrum of values of v for which there exists a1-rotational STS(v) under a cyclic, an abelian, or a generalized quaternion group, has beenestablished in 1981 (phelps and Rosa), in 2001 (Buratti) and in 2008 (Mishima), respectively.Nevertheless, the spectrum of values of v for which there exists a1-rotational STS(v) under an arbitrary group has not been completely determined yet.This paper is a considerable step forward to the solution of this problem.In fact, we leave as uncertain cases only those for which we have v = (p^3-p)n + 1 = 1 (mod 96)with p a prime, n =1,2,3 mod 4, and the odd part of (p^3-p)n that is square-free and without prime factors congruent to 1 mod 6
2-Starters, Graceful Labelings, and a Doubling Construction for the Oberwolfach Problem
No full textEvery 1-rotational solution of a classic or twofold Oberwolfach problem (OP) of order n is generated by a suitable 2-factor (starter) of or , respectively. It is shown that any starter of a twofold OP of order n gives rise to a starter of a classic OP of order 2n-1 (doubling construction). It is also shown that by suitably modifying the starter of a classic OP, one may obtain starters of some other OPs of the same order but having different parameters. The combination of these two constructions leads to lots of new infinite classes of solvable OPs. Still more classes can be obtained with the help of a third construction making use of the possible gracefulness of a graph whose connected components are cycles and at most one path. As one of the many applications, Hilton and Johnson's [J London Math Soc, 64 (2001) 513–522] bound about the solvability of OP(r,s) is improved to in the case of r even
Pairwise balanced designs from finite fields
No full textAbstractDeveloping previous work by R.C. Bose, R.M. Wilson, M. Greig and the author, we give a general construction for difference families over finite fields. All the DFs constructed before were generated by a single initial base block so that they were uniform. Here we also consider DFs generated by two or more initial base blocks. These DFs give rise to pairwise balanced designs which of course are balanced block designs exactly when the initial base blocks have constant size
Z-cyclic (t,8)GWhD(v), t=2,4
No full textGeneralized whist tournament designs are resolvable or near-resolvable -designs in which each block of size is partitioned into teams of players each; every two players appear in exactly games as teammates and in exactly games as opponents. In this paper the cases when and are treated under the additional assumption that the design is cyclic or 1-rotational (that is, -cyclic). Existence is settled affirmatively when and is a prime, with two exceptions. Consequences for the existence of other whist tournament designs are examined
Cycle decompositions with a sharply vertex transitive automorphism group
No full textIn some recent papers the method of partial differences introduced by the author [4] was very helpful in the construction of cyclic cycle systems. Here we use this method for the purpose of constructing, more generally, cycle decompositions with a sharply vertex transitive automorphism group not necessarily cyclic
On the Buratti-Horak-Rosa Conjecture about Hamiltonian Paths in Complete Graphs
No full textIn this paper we investigate a problem proposed by Marco Buratti, Peter Horak and Alex Rosa (denoted by BHR-problem) concerning Hamiltonian paths in the complete graph with prescribed edge-lengths. In particular we solve BHR({1^a,2^b,t^c}) for any even integer t≥4, provided that a+b≥t−1. Furthermore, for t=4,6,8 we present a complete solution of BHR({1^a,2^b,t^c}) for any positive integer a,b,c
Pairwise balanced designs from finite fields
No full textDeveloping previous work by R.C. Bose, R.M. Wilson, M. Greig and the author, we give a general construction for difference families over fnite fields. All the DFs constructed before were generated by a single initial base block so that they were uniform. Here we also consider DFs generated by two or more initial base blocks. These DFs give rise to pairwise balanced designs which of course are balanced block designs exactly when the initial base blocks have constant size
Masonry wall panels retrofitted with thermal-insulating GFRP-reinforced jacketing
No full textToday there is a need to provide thermally efficient walls, while at the same time to increase the mechanical properties of old unreinforced masonry walls that will not require large amounts of energy in the retrofitting or deconstruction processes. To address this problem, this paper gives the results of shear tests carried out on masonry panels made of solid bricks retrofitted with a new technique based on the use of glass fiber-reinforced polymers (GFRP) grids inserted into a thermal insulating jacketing. This was made of different low-strength lime-based mortars. Tests were carried out in laboratory and results were used for the determination of the shear modulus and strength of the wall panels before and after the application of the GFRP reinforcement. Retrofitted panels exhibited a significant enhancement in the lateral capacity when compared to the control panels. The thermal performance of the proposed mortars was also investigated both with and without GFRP. Low values of thermal conductivity were found, especially for the samples with GFRP; a reduction of the thermal transmittance value in the 34–45 % range was also obtained by applying 45 mm layer of coating in conventional masonry walls
A reduction of the spectrum problem for odd sun systems and the prime case
No full textA k-cycle with a pendant edge attached to each vertex is called a k-sun. The existence problem for k-sun decompositions of Kv, with k odd, has been solved only when k = 3 or 5. By adapting a method used by Hoffmann, Lindner, and Rodger to reduce the spectrum problem for odd cycle systems of the complete graph, we show that if there is a (Formula presented.) -sun system of (Formula presented.) ((Formula presented.) odd) whenever (Formula presented.) lies in the range (Formula presented.) and satisfies the obvious necessary conditions, then such a system exists for every admissible (Formula presented.). Furthermore, we give a complete solution whenever k is an odd prime
Experiential Perspective in Management Literature: A Systematic Review
No full textThe first chapter describes the evolution of the state state-of-the-art of the experiential perspective (ExP) approach in managerial literature, an approach that uses the concept of customer experience management (CEM) in a variety of ways. Through a systematic review, the chapter provides a structured overview of the main studies that use the experiential perspective; this overview is instrumental to in the conceptual scheme of the book developed in the chapter Marketing in an experiential perspective: from “goods and services logic” to “experience logic.” To describe the various approaches in which the authors classify articles, authors, and journals of reference in experiential perspective and customer experience management (ExP and CEM), the authors measure the notoriety of the articles and their authors, in an attempt to assess whether and how their impact dwindles inside the “small world” of ExP and CEM, or whether, instead, it extends to a wider radius that includes management literature. Lastly, the authors define the areas of application (areas of interest, or sectors), where the concept has found its widest application. The chapter, recognizing that the experiential logic is assuming centrality in marketing studies, indicates the need to construct a key to understanding and a conceptual basis of synthesis capable of integrating the various contributions that emerged in the literature into a unified framework
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