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81.
Vojtěch Jarník 《Mathematische Zeitschrift》1931,33(1):62-84
Ohne Zusammenfassung 相似文献
82.
Fort=2,3 andk2t–1 we prove the existence oft–(n,k,) designs with independence numberC
,k
n
(k–t)/(k–1)
(ln n)
1/(k–1)
. This is, up to the constant factor, the best possible.Some other related results are considered.Supported by NSF Grant DMS-9011850 相似文献
83.
LetG=(V, E) be a graph withn vertices. The direct product dimension pdim (G) (c.f. [10], [12]) is the minimum numbert such thatG can be embedded into a product oft copies of complete graphsK
n.In [10], Lovász, Neetil and Pultr determined the direct product dimension of matchings and paths and gave sharp bounds for the product dimension of cycles, all logarithmic in the number of vertices. 相似文献
84.
Dey Sukalpa Banerjee Pradyot Gangopadhyay Sumana Vojtíšek Pavel 《Transition Metal Chemistry》2003,28(7):765-771
The synthesis of six mononuclear palladium complexes of general formula [Pd(ox)/(mal)L2] and [Pd(ox)/(mal)L] (ox = oxalate, mal = malonate, both L and L are vitamin-B6 molecules (I), L = pyridoxine, pyridoxal and L = pyridoxamine) has been achieved. The structures of these compounds were established by elemental analysis, i.r. and 13C-n.m.r. [Pd(oxalate)(pyridoxine)2] was analyzed by single crystal X-ray diffraction. It exhibits square planar coordination with bond lengths 2.015 (2) Å for Pd—N and 2.010 (2) Å for Pd—O. The interaction of [Pd(ox)2]2– and [Pd(mal)2]2– with L has been followed kinetically in order to look into the nature of products and the mechanism of formation under the conditions [PdII-chelate] [L] and [L]. 相似文献
85.
It is proved that for every finite latticeL there exists a finite latticeL such that for every partition of the points ofL into two classes there exists a lattice embeddingf:LL such that the points off(L) are in one of the classes.This property is called point-Ramsey property of the class of all finite lattices. In fact a stronger theorem is proved which implies the following: for everyn there exists a finite latticeL such that the Hasse-diagram (=covering relation) has chromatic number >n. We discuss the validity of Ramseytype theorems in the classes of finite posets (where a full discussion is given) and finite distributive lattices. Finally we prove theorems which deal with partitions of lattices into an unbounded number of classes.Presented by G. Grätzer. 相似文献
86.
87.
The number α, 0≦α≦1, is a jump forr if for any positive ε and any integerm,m≧r, anyr-uniform hypergraph withn>n o (ε,m) vertices and at least (α+ε) \(\left( {\begin{array}{*{20}c} n \\ r \\ \end{array} } \right)\) edges contains a subgraph withm vertices and at least (α+c) \(\left( {\begin{array}{*{20}c} m \\ r \\ \end{array} } \right)\) edges, wherec=c(α) does not depend on ε andm. It follows from a theorem of Erdös, Stone and Simonovits that forr=2 every α is a jump. Erdös asked whether the same is true forr≧3. He offered $ 1000 for answering this question. In this paper we give a negative answer by showing that \(1 - \frac{1}{{l^{r - 1} }}\) is not a jump ifr≧3,l>2r. 相似文献
88.
Nonadiabatic coupling between the lowest two singlet potential energy surfaces of the Li-Li
2
+
system is calculated using the diatomics-in-molecules method. Location of nonadiabatic regions in the configuration space of Li-Li
2
+
and their analysis is used to estimate those inner and translational states of the reactants which can lead to nonadiabatic behavior. 相似文献
89.
Shaikh N Panja A Goswami S Banerjee P Vojtísek P Zhang YZ Su G Gao S 《Inorganic chemistry》2004,43(3):849-851
A layered mixed-valence manganese complex, [Mn(II)(2)(bispicen)(2)(mu(3)-Cl)(2)Mn(III)(Cl(4)Cat)(2)Mn(III)(Cl(4)Cat)(2)(H(2)O)(2)](infinity), is synthesized and characterized structurally. It displays a slow magnetic relaxation and hysteresis effect. 相似文献
90.