共查询到20条相似文献,搜索用时 770 毫秒
1.
M. Drew LaMar 《Discrete Mathematics》2012,312(7):1314-1325
We generalize the class of split graphs to the directed case and show that these split digraphs can be identified from their degree sequences. The first degree sequence characterization is an extension of the concept of splittance to directed graphs, while the second characterization says a digraph is split if and only if its degree sequence satisfies one of the Fulkerson inequalities (which determine when an integer-pair sequence is digraphic) with equality. 相似文献
2.
ANTONIO J CALDERóN MARTíN MANUEL FORERO PIULESTáN JOSé M SáNCHEZ DELGADO 《Proceedings Mathematical Sciences》2012,122(2):181-187
We study the structure of split Malcev algebras of arbitrary dimension over an algebraically closed field of characteristic zero. We show that any such algebras M is of the form $M={\mathcal U} +\sum_{j}I_{j}$ with ${\mathcal U}$ a subspace of the abelian Malcev subalgebra H and any I j a well described ideal of M satisfying [I j ,I k ]?=?0 if j????k. Under certain conditions, the simplicity of M is characterized and it is shown that M is the direct sum of a semisimple split Lie algebra and a direct sum of simple non-Lie Malcev algebras. 相似文献
3.
The so-called split IC quasi-adequate semigroups are in the class of idempotent-connected quasi-adequate semigroups. It is
proved that an IC quasi-adequate semigroup is split if and only if it has an adequate transversal. The structure of such semigroup
whose band of idempotents is regular will be particularly investigated. Our obtained results enrich those results given by
McAlister and Blyth on split orthodox semigroups. 相似文献
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The class of split permutation graphs is the intersection of two important classes, the split graphs and permutation graphs. It also contains an important subclass, the threshold graphs. The class of threshold graphs enjoys many nice properties. In particular, these graphs have bounded clique-width and they are well-quasi-ordered by the induced subgraph relation. It is known that neither of these two properties is extendable to split graphs or to permutation graphs. In the present paper, we study the question of extendability of these two properties to split permutation graphs. We answer this question negatively with respect to both properties. Moreover, we conjecture that with respect to both of them the split permutation graphs constitute a critical class. 相似文献
6.
A poset P=(X,) is a split semiorder if a unit interval and a distinguished point in that interval can be assigned to each xX so that xy precisely when x's distinguished point precedes y's interval, and y's distinguished point follows x's interval. For each |X|10, we count the split semiorders and identify all posets that are minimal forbidden posets for split semiorders. 相似文献
7.
A partial isometry V is said to be a split partial isometry if ${\mathcal{H}=R(V) + N(V)}$ , with R(V) ∩ N(V) = {0} (R(V) = range of V, N(V) = null-space of V). We study the topological properties of the set ${\mathcal{I}_0}$ of such partial isometries. Denote by ${\mathcal{I}}$ the set of all partial isometries of ${\mathcal{B}(\mathcal{H})}$ , and by ${\mathcal{I}_N}$ the set of normal partial isometries. Then $$\mathcal{I}_N\subset \mathcal{I}_0\subset \mathcal{I}, $$ and the inclusions are proper. It is known that ${\mathcal{I}}$ is a C ∞-submanifold of ${\mathcal{B}(\mathcal{H})}$ . It is shown here that ${\mathcal{I}_0}$ is open in ${\mathcal{I}}$ , therefore is has also C ∞-local structure. We characterize the set ${\mathcal{I}_0}$ , in terms of metric properties, existence of special pseudo-inverses, and a property of the spectrum and the resolvent of V. The connected components of ${\mathcal{I}_0}$ are characterized: ${V_0,V_1\in \mathcal{I}_0}$ lie in the same connected component if and only if $${\rm dim}\, R(V_0)= {\rm dim}\, R(V_1) \,\,{\rm and}\,\,\, {\rm dim}\, R(V_0)^\perp = {\rm dim}\, R(V_1)^\perp.$$ This result is known for normal partial isometries. 相似文献
8.
Mahmut Akyiğit Hidayet Hüda Kösal Murat Tosun 《Advances in Applied Clifford Algebras》2013,23(3):535-545
Starting from ideas given by Horadam in [5] , in this paper, we will define the split Fibonacci quaternion, the split Lucas quaternion and the split generalized Fibonacci quaternion. We used the well-known identities related to the Fibonacci and Lucas numbers to obtain the relations between the split Fibonacci, split Lucas and the split generalized Fibonacci quaternions. Moreover, we give Binet formulas and Cassini identities for these quaternions. 相似文献
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A left GC-lpp semigroup S is called split if the natural homomorphism γb of S onto S/γ induced by γ is split.It is proved that a left GC-lpp semigroup is split if and only if it has a left adequate transversal.In particular,a construction theorem for split left GC-lpp semigroups is established. 相似文献
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12.
A left GC-lpp semigroup S is called split if the natural homomorphism γb of S onto S/γ induced by γ is split.It is proved that a left GC-lpp semigroup is split if and only if it has a left adequate transversal.In particular,a construction theorem for split left GC-lpp semigroups is established. 相似文献
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Split Monotone Variational Inclusions 总被引:2,自引:0,他引:2
A. Moudafi 《Journal of Optimization Theory and Applications》2011,150(2):275-283
Based on the very recent work by Censor-Gibali-Reich (), we propose an extension of their new variational problem (Split Variational Inequality Problem) to monotone variational
inclusions. Relying on the Krasnosel’skii-Mann Theorem for averaged operators, we analyze an algorithm for solving new split
monotone inclusions under weaker conditions. Our weak convergence results improve and develop previously discussed Split Variational
Inequality Problems, feasibility problems and related problems and algorithms. 相似文献
15.
A poset P=(X,P) is a split semiorder when there exists a function I thatassigns to each x X a closed interval
of the real line R and a set
of real numbers, with
, suchthat x<y in P if and only if
and
in R. Every semiorder is a split semiorder, and thereare split semiorders which are not interval orders. It is well known thatthe dimension of a semiorder is at most 3. We prove that the dimension of asplit semiorder is at most 6. We note also that some split semiorders havesemiorder dimension at least 3, and that every split semiorder has intervaldimension at most 2. 相似文献
16.
A poset (X,) is a split interval order (a.k.a. unit bitolerance order, proper bitolerance order) if a real interval and a distinguished point in that interval can be assigned to each xX so that xy precisely when x's distinguished point precedes y's interval, and x's interval precedes y's distinguished point. For each |X|9, we count the split interval orders and identify all posets that are minimal forbidden posets for split interval orders. The paper is a companion to Counting Split Semiorders by Fishburn and Reeds (this issue). 相似文献
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18.
Grigory D. Solomadin 《Proceedings of the Steklov Institute of Mathematics》2018,302(1):358-379
A smooth stably complex manifold is called a totally tangentially/normally split manifold (TTS/TNS manifold for short) if the respective complex tangential/normal vector bundle is stably isomorphic to a Whitney sum of complex line bundles, respectively. In this paper we construct manifolds M such that any complex vector bundle over M is stably equivalent to a Whitney sum of complex line bundles. A quasitoric manifold shares this property if and only if it is a TNS manifold. We establish a new criterion for a quasitoric manifold M to be TNS via non-semidefiniteness of certain higher degree forms in the respective cohomology ring of M. In the family of quasitoric manifolds, this generalizes the theorem of J. Lannes about the signature of a simply connected stably complex TNS 4-manifold. We apply our criterion to show the flag property of the moment polytope for a nonsingular toric projective TNS manifold of complex dimension 3. 相似文献
19.
Let $\mathcal A$ be an exact category, that is, an extension-closed full subcategory of an abelian category. First, we give new characterizations of an almost split sequence in $\mathcal{A}$ , which yields some necessary and sufficient conditions for $\mathcal A$ to have almost split sequences. Then, we study when an almost split sequence in $\mathcal A$ induces an almost split sequence in an exact subcategory $\mathcal C$ of $\mathcal A$ . In case $\mathcal A$ has almost split sequences and $\mathcal C$ is Ext-finite and Krull–Schmidt, we obtain a necessary and sufficient condition for $\mathcal C$ to have almost split sequences. Finally, we show some applications of these results. 相似文献