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141.
Bin Zhu 《Journal of Algebraic Combinatorics》2008,27(1):35-54
We give a quiver representation theoretic interpretation of generalized cluster complexes defined by Fomin and Reading. Using
d-cluster categories defined by Keller as triangulated orbit categories of (bounded) derived categories of representations
of valued quivers, we define a d-compatibility degree (−∥−) on any pair of “colored” almost positive real Schur roots which generalizes previous definitions on the noncolored case
and call two such roots compatible, provided that their d-compatibility degree is zero. Associated to the root system Φ corresponding to the valued quiver, using this compatibility relation, we define a simplicial complex which has colored almost
positive real Schur roots as vertices and d-compatible subsets as simplices. If the valued quiver is an alternating quiver of a Dynkin diagram, then this complex is
the generalized cluster complex defined by Fomin and Reading.
Supported by the NSF of China (Grants 10471071) and by the Leverhulme Trust through the network ‘Algebras, Representations
and Applications’. 相似文献
142.
143.
In this note we prove that half of all homotopy classes of almost complex structures on M is not compatible with any symplectic structure for a certain class of oriented compact 4-manifolds M. In particular, half of all homotopy classes of almost complex structures on an oriented 4-manifold is not compatible to any Kähler structure. 相似文献
144.
时延细胞神经网络的概周期解的存在性和指数稳定性 总被引:1,自引:0,他引:1
研究时延细胞神经网络的概周期解存在性和全局指数稳定性问题 ,巧妙地引入可调实参数di>0 (i =1,2 ,… ,n) ,获得了该神经网络存在唯一的概周期解的充分条件和所有其它解均指数地收敛于此概周期解的充分条件 . 相似文献
145.
Jan Kucera 《Czechoslovak Mathematical Journal》2004,54(1):103-106
An inductive locally convex limit of reflexive topological spaces is reflexive iff it is almost regular. 相似文献
146.
Chuanyi Zhang 《Czechoslovak Mathematical Journal》1997,47(3):385-394
Vector-valued pseudo almost periodic functions are defined and their properties are investigated. The vector-valued functions contain many known functions as special cases. A unique decomposition theorem is given to show that a vector-valued pseudo almost periodic function is a sum of an almost periodic function and an ergodic perturbation. 相似文献
147.
A variety of processes can be modeled by the irreversible cooperative filling of lattice sites. We consider here cases where the filling rate is independent of the state of the surrounding sitesexcept when all nearest neighbors are already filled (where a generally different rate operates) and indicate some applications for such choices. Exact solutions are obtained to the hierarchical form of the master equations for subconfiguration probabilities for a lattice of arbitrary dimension or coordination number. Analogous irreversible coadsorption processes and processes with longer-range cooperative effects, also amenable to exact solution, are discussed.Ames Laboratory is operated for the U.S. Department of Energy under Contract No. W-7405-ENG-82. This work was supported by the Office of Basic Energy Sciences. 相似文献
148.
We construct connected, locally connected, almost regular, countable, Urysohn spaces. This answers a problem of G.X. Ritter. We show that there are 2c such non-homeomorphic spaces. We also show that there are 2c non-homeomorphic spaces which are further rigid. We discuss the group of homeomorphisms of such spaces.The following question was raised by G.X. Ritter: Does there exist a countable connected locally connected Urysohn space which is almost regular? We answer this question in the affirmative and in fact, show that not only are there as many as 2c such spaces but that there are just as many rigid spaces with the same properties. Furthermore we show that every countable Urysohn space is a subspace of such a space. We also prove that every countable group is isomorphic to the group of autohomeomorphisms of some connected locally connected almost regular Urysohn space. Examples are given of groups of order c which can be represented in this manner. 相似文献
149.
We prove that for Hilbert space operators and , it follows that
where . Using the concept of -Gateaux derivative, we apply this result to characterize orthogonality in the sense of James in , and to give an easy proof of the characterization of smooth points in .
,\end{displaymath}">
where . Using the concept of -Gateaux derivative, we apply this result to characterize orthogonality in the sense of James in , and to give an easy proof of the characterization of smooth points in .
150.
Motivated by problems occurring in the empirical identification and modelling of a n-dimensional ARMA time series X(t) we study the possibility of obtaining a factorization (I + a1B + … + apBp) X(t) = [Πi=1p (I ? αiB)] X(t), where B is the backward shift operator. Using a result in [3] we conclude that as in the univariate case such a factorization always exists, but unlike the univariate case in general the factorization is not unique for given a1, a2,…, ap. In fact the number of possibilities is limited upwards by , there being cases, however, where this maximum is not reached. Implications for the existence and possible use of transformations which removes nonstationarity (or almost nonstationarity) of X(t) are mentioned. 相似文献