共查询到20条相似文献,搜索用时 93 毫秒
1.
《代数通讯》2013,41(9):3759-3771
An algebra is called right-symmetric, if it satisfies the identity a ? (b ? c ? c ? b) = (a ? b) ? c ? (a ? c) ? b. Right-symmetric algebras over a field of characteristic p are considered. A formula for the p-th power of a sum of two elements of right-symmetric algebras is established. The formula is similar to Jacobson formula for the p-th power of a sum of two elements of Lie algebras. 相似文献
2.
Joaquín Borrego-Díaz Alejandro Fernndez-Margarit Mario Prez-Jimnez 《Mathematical Logic Quarterly》1996,42(1):341-348
We study the theories I?n, L?n and overspill principles for ?n formulas. We show that IEn ? L?n ? I?n, but we do not know if I?n L?n. We introduce a new scheme, the growth scheme Crγ, and we prove that L?n ? Cr?n? I?n. Also, we analyse the utility of bounded collection axioms for the study of the above theories. Mathematics Subject Classification: 03F30, 03H15. 相似文献
3.
George R. T. Hendry 《Journal of Graph Theory》1988,12(4):491-497
For integers p and s satisfying 2 ? s ? p ? 1, let m(p,s) denote the maximum number of edges in a graph G of order p such that the minimum degree in the hamiltonian path graph of G equals s. The values of m(p, s) are determined for 2 ? s ? p/2 and for (2p ? 2)/3 ? s ? p ? 1, and upper and lower bounds on m(p, s) are obtained for p/2 < s < (2p ? 2)/3. 相似文献
4.
Stanley P. Hutton 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1958,9(5-6):357-371
Zusammenfassung Es wird die an einem Axialventilator durchgeführte Untersuchung der Auswirkung des Schaufelspaltes auf Laufradstr?mung und
Leistung beschrieben. Das Laufrad, mit einem Durchmesser von 305 mm, war für ausgepr?gt dreidimensionale Str?mung entworfen.
Die in solchen F?llen bestehenden Einschr?nkungen der Gültigkeit von zweidimensionalen Berechnungsunterlagen aus Windkanalversuchen
werden besprochen.
Es zeigte sich, dass die radial nach aussen gerichtete Querstr?mung durch Zentrifugalwirkung und die nach innen gerichtete
Querstr?mung durch Vergr?sserung des Spaltspieles hervorgerufen wird. Vergr?sserung der Spaltweite beeinflusst die Str?mungsverh?ltnisse
nicht nur in der N?he der Schaufelspitze, sondern über die ganze radiale Erstreckung der Schaufel. Dadurch wird die Druckziffer
verkleinert, und die Abreissbedingungen ver?ndern sich.
Unter diesen Verh?ltnissen ist es wesentlich, die ?nderung der Axialgeschwindigkeit im Laufrad korrekt in Rechnung zu setzen.
Der wesentlichste Parameter scheint die Gr?ssec
2m
/u zu sein. Dabei zeichnet sich bei gleichen Eintrittsverh?ltnissen, aber stark verschiedenen Querstr?mungen ein eindeutiger
Zusammenhang zwischenc
2u
/c
2m
undc
2m
/u für beliebige Schaufelgeometrien ab. Es mag daher von Vorteil sein, den aus Messungen am zweidimensionalen Windkanal erhaltenen
Unterlagen in dieser Form den Vorzug vor den üblichen Einzelflügel- und Gitterparametern zu geben, die durch Querstr?mung
merklich beeinflusst werden.
相似文献
5.
Thomas Wanner 《Journal of Graph Theory》1989,13(5):597-605
We show that a graph G on n ? q + 1 vertices (where q ? 2) has the chromatic polynomial P(G;λ) = λ(λ ? 1) … (λ ? q + 2) (λ ? q + 1)2 (λ ? q)n?q?1 if and only if G can be obtained from a q-tree Ton n vertices by deleting an edge contained in exactly q ? 1 triangles of T. Furthermore, we prove that these graphs are triangulated. 相似文献
6.
Cun-Quan Zhang 《Journal of Graph Theory》1989,13(4):485-490
Let G be 2-connected graph with girth g and minimum degree d. Then each pair of vertices of G is joined by a path of length at least max{1/2(d ? 1)g, (d ? 3/2)(g ? 4) + 2} if g ? 4, and the length of a longest cycle of G is at least max{[(d ? 1)(g ? 2) + 2], [(2d ? 3)(g ? 4) + 4]}. 相似文献
7.
David Hilbert 《Acta Mathematica》1902,26(1):99-131
Ohne Zusammenfassung
Mit geringen ?nderungen abgedruckt aus den Nachrichten der Kgl. Ges. der Wiss. zu G?ttingen 1898.
Inzwischen sind folgende auf diesen Gegenstand bezügliche Inaugural-Dissertationen in G?ttingen erschienen:Das quadratische Reciprocit?tsgesetz im quadratischen Zahlk?rper mit der Classenzahl 1. vonH. D?rrie 1898,Tafel der Klassenanzahlen für kubische Zahlk?rper vonL. W. Reid 1899,Das allgemeine quadratische Reciprocit?tsgesetz in ausgew?hlten Kreisk?rpern der 2
h ten
Einheitswurzeln vonK. S. Hilbert 1900,Quadratische Reciprocit?tsgesetze in algebraischen Zahlk?rpern vonG. Rückle 1901. Insbesondere die letzte Dissertation enth?lt zahlreiche und interessante Beispiele zu der hier entwickelten Theorie. 相似文献
8.
C. Molitor-Braun 《manuscripta mathematica》1998,96(1):23-35
Let V be an exponential ?-module, ? being an exponential Lie algebra. Put ? = exp ?. Then every orbit of V under the action of ? admits a closed orbit in its closure. If G= exp ? is a nilpotent Lie group and ? an exponential algebra of derivations of ?, then ? = exp ? acts on G, L
1(G), (?) and the maximal ?-invariant ideals of L
1(G), resp. of (?) coincide with the kernels Ker Ω, resp. Ker Ω∩ (?), where Ω is a closed orbit of ?*.
Received: 6 December 1996 / Revised version: 7 December 1997 相似文献
9.
For a simple planar graph G and a positive integer k, we prove the upper bound 2(n ? 1)k + 4k(n ? 4) + 2·3k ? 2((δ + 1)k ? δk)(3n ? 6 ? m) on the sum of the kth powers of the degrees of G, where n, m, and δ are the order, the size, and the minimum degree of G, respectively. The bound is tight for all m with 0?3n ? 6 ? m≤?n/2? ? 2 and δ = 3. We also present upper bounds in terms of order, minimum degree, and maximum degree of G. © 2010 Wiley Periodicals, Inc. J Graph Theory 67:112‐123, 2011 相似文献
10.
Uwe Franken 《Mathematische Nachrichten》1993,164(1):119-139
For a weight function ω and a closed set A ? ?N let ?(ω)(A) denote the space of all ω-Whitney jets of Beurling type on A. It is shown that for each closed set A ? ?N there exists an ω-extension operator EA: ?(ω)(A) → ?(ω)(?N) if and only if ω is a (DN)-function (see MEISE and TAYLOR [18], 3.3). Moreover for a fixed compact set K ? ?N there exists an ω-extension operator EK: ?(ω)(K) → ?(ω)(?N) if and only if the Fréchet space ?(ω)(K) satisfies the property (DN) (see Vogt [29], 1.1.). 相似文献
11.
Sean McGuinness 《Graphs and Combinatorics》2001,17(1):135-148
Let ? be the family of finite collections ? where ? is a collection of bounded, arcwise connected sets in ℝ2 where for any S,T∈? such that S∩T≠?, it holds that S∩T is arcwise connected. Given ? is triangle-free, and provided the chromatic number χ(G) of the intersection graph G=G(?) of ? is sufficiently large, there exists α>1 independent of ? such that there is a subcollection ?′⊂? of at most 5 sets with the property that the sets of ? surrounded by ?′ induce an intersection graph H where .
Received: November 13, 1995 Final version received: December 3, 1998 相似文献
12.
Cai Mao-Cheng 《Journal of Graph Theory》1991,15(3):283-301
Let a and b be integers with b ? a ? 0. A graph G is called an [a,b]-graph if a ? dG(v) ? b for each vertex v ∈ V(G), and an [a,b]-factor of a graph G is a spanning [a,b]-subgraph of G. A graph is [a,b]-factorable if its edges can be decomposed into [a,b]-factors. The purpose of this paper is to prove the following three theorems: (i) if 1 ? b ? 2a, every [(12a + 2)m + 2an,(12b + 4)m + 2bn]-graph is [2a, 2b + 1]-factorable; (ii) if b ? 2a ?1, every [(12a ?4)m + 2an, (12b ?2)m + 2bn]-graph is [2a ?1,2b]-factorable; and (iii) if b ? 2a ?1, every [(6a ?2)m + 2an, (6b + 2)m + 2bn]-graph is [2a ?1,2b + 1]-factorable, where m and n are nonnegative integers. They generalize some [a,b]-factorization results of Akiyama and Kano [3], Kano [6], and Era [5]. 相似文献
13.
Joseph Barback 《Mathematical Logic Quarterly》1998,44(2):229-264
In this paper we introduce a collection of isols having some interesting properties. Imagine a collection W of regressive isols with the following features: (1) u, v ? W implies that u ? v or v ? u, (2) u ? v and v ? W imply u ? W, (3) W contains ? = {0,1,2,…} and some infinite isols, and (4) u e? W, u infinite, and u + v regressive imply u + v ? W. That such a collection W exists is proved in our paper. It has many nice features. It also satisfies (5) u, v ? W, u ? v and u infinite imply v ? g(u) for some recursive combinatorial function g, and (6) each u ? W is hereditarily odd-even and is hereditarily recursively strongly torre. The collection W that we obtain may be characterized in terms of a semiring of isols D(c) introduced by J. C. E. Dekker in [5]. We will show that W = D(c), where c is an infinite regressive isol that is called completely torre. 相似文献
14.
《复变函数与椭圆型方程》2012,57(11):967-985
We show that a domain R ? ? has the property that ?(𝔻) is a quasidisk for all ? for which ?v′(𝔻) ? R if and only if there is a compact K ? ? such that rK ∩ (?\R) ≠ Ø for all r > 0. This constitutes a refinement of the well-known Noshiro–Warschawski univalence criterion. 相似文献
15.
Qing-Xue Huang 《Journal of Graph Theory》1993,17(6):727-754
Let αm(n) denote the minimum number of edge-disjoint complete m-partite subgraphs into which Kn can be decomposed. In [2] the author proved that when m ≥ 3, if (i) n ≡ m and n ≡ m (mod m ?1), or (ii) b ∈ [2, m ?1], n ≥ b(m ?1) + m ? (b ?1), and n ≡ b(m ?1) + m ? (b ?1) (mod m? 1), then αm(n) = ?(n + m ?3)/(m ?1)? (= ?(n ?1)/(m ?1)?), and that for every integer n, if Kn has an edge-disjoint complete m-partite subgraph decomposition, then αm(n) ≥ ?(n? 1)/(m? 1)?. In this paper we generally discuss the question as to which integers n's satisfy (or do not) αm(n) = ?(n ?1)/(m ?1)?. Here we also study the methods to find these integers; the methods are themselves interesting. Our main results are Theorem 2.11, 2.12, and 2.16. Besides, Theorem 2.4 and 2.6 are interesting results too. © 1993 John Wiley & Sons, Inc. 相似文献
16.
A graph is said to be K1,n-free, if it contains no K1,n as an induced subgraph. We prove that for n ? 3 and r ? n ?1, if G is a K1,n-free graph with minimum degree at least (n2/4(n ?1))r + (3n ?6)/2 + (n ?1)/4r, then G has an r-factor (in the case where r is even, the condition r ? n ?1 can be dropped). 相似文献
17.
Let ?1 ? ?2 be classes of right R-modules, we introduce ?1-covering modules and projective modules relative to ?2 to characterize the relations between the existences of ?1-covers, ?2-covers and the classes ?1, ?2. As corollaries, every module in ? n is an ?-covering module if and only if every flat cover is an ? n -cover for each right module if and only if R is a von Neumann regular ring whenever wD(R) < ∞; every flat right R-module is projective relative to 𝒫 if and only if every flat cover is a projective cover for each right module if and only if R is right perfect. 相似文献
18.
Résumé On dit qu’un homomorphismef :A →B d’anneaux commutatifs est un morphisme de cha?ne (resp., den-cha?ne pour un entiern ≥ 1) si toute cha?ne d’idéaux premiers (resp., d’au plusn idéaux premiers) deA se relève en une cha?ne d’idéaux premiers deB. Sif est un morphisme den-cha?ne, alorsf n’est pas forcément un morphisme de (n + 1)-cha?ne, même siA etB sont des anneaux intègres, doncf n’est pas un morphisme de cha?ne. Sif est un morphisme den-cha?ne pour toutn, alorsf est un morphisme de cha?ne. Un morphisme de cha?ne n’est pas forcément un morphisme de cha?ne universel. Pour tout entiern ≥ 2,f est universellement un morphisme den-cha?ne si et seulement sif est universellement un morphisme de cha?ne. Un morphisme qui est universellement de cha?ne et universellement incomparable
n’est pas nécessairement entier, même siA etB sont des anneaux intègres de dimension 1 (au sens de Krull).
相似文献
19.
It is shown that for several important classes of commutative rings, L? and O? are equivalent. In particular, a commutative artinian ring is L? if and only if it is O?. More examples of O?-fields are provided. 相似文献
20.
Let ? be a symmetric binary function, positive valued on positive arguments. A graph G = (V,E) is a ?‐tolerance graph if each vertex υ ∈ V can be assigned a closed interval Iυ and a positive tolerance tυ so that xy ∈ E ? | Ix ∩ Iy|≥ ? (tx,ty). An Archimedean function has the property of tending to infinity whenever one of its arguments tends to infinity. Generalizing a known result of [15] for trees, we prove that every graph in a large class (which includes all chordless suns and cacti and the complete bipartite graphs K2,k) is a ?‐tolerance graph for all Archimedean functions ?. This property does not hold for most graphs. Next, we present the result that every graph G can be represented as a ?G‐tolerance graph for some Archimedean polynomial ?G. Finally, we prove that there is a ?universal”? Archimedean function ? * such that every graph G is a ?*‐tolerance graph. © 2002 Wiley Periodicals, Inc. J Graph Theory 41: 179–194, 2002 相似文献