Lower bound for the mean project completion time in dynamic PERT networks

We apply the stochastic dynamic programming to obtain a lower bound for the mean project completion time in a PERT network, where the activity durations are exponentially distributed random variables. Moreover, these random variables are non-static in that the distributions themselves vary according to some randomness in society like strike or inflation. This social randomness is modelled as a function of a separate continuous-time Markov process over the time horizon. The results are verified by simulation.     

Moore bound for mixed networks

Mixed graphs contain both undirected as well as directed links between vertices and therefore are an interesting model for interconnection communication networks. In this paper, we establish the Moore bound for mixed graphs, which generalizes both the directed and the undirected Moore bound.     

Lower bound for a linear form

By using Padé approximations of the first kind, we obtain a lower bound for the absolute value of a linear form with integer coefficients from the values of polylogarithmic functions at rational points. This estimate takes into account the growth of all coefficients of the linear form. Translated fromMatematicheskie Zametki, Vol. 66, No. 4, pp. 617–623, October, 1999.     

Lower bound theorem for normal pseudomanifolds

In this paper we present a self-contained combinatorial proof of the lower bound theorem for normal pseudomanifolds, including a treatment of the cases of equality in this theorem. We also discuss McMullen and Walkup's generalized lower bound conjecture for triangulated spheres in the context of the lower bound theorem. Finally, we pose a new lower bound conjecture for non-simply connected triangulated manifolds.     

A lower bound for algebraic connectivity based on the connection-graph-stability method

This paper introduces the connection-graph-stability method and uses it to establish a new lower bound on the algebraic connectivity of graphs (the second smallest eigenvalue of the Laplacian matrix of the graph) that is sharper than the previously published bounds. The connection-graph-stability score for each edge is defined as the sum of the lengths of the shortest paths making use of that edge. We prove that the algebraic connectivity of the graph is bounded below by the size of the graph divided by the maximum connection-graph-stability score assigned to the edges.     

The existence and upper bound for two types of restricted connectivity

In this paper, we study two types of restricted connectivity: κ_k(G) is the cardinality of a minimum vertex cut S such that every component of G−S has at least k vertices; is the cardinality of a minimum vertex cut S such that there are at least two components in G−S of order at least k. In this paper, we give some sufficient conditions for the existence and upper bound of κ_k(G) and/or , and study some properties of these two parameters.     

Lower bound for the maximum of a stochastic process

The first author's participation in the preparation of this paper was supported by the Russian Foundation for Basic Research (Grant No. 93-01-00240).     

Lower bound inequalities for norms of symmetrized tensor powers

Let V be a complex inner product space of positive dimension m with inner product 〈·,·〉, and let T_n(V) denote the set of all n-linear complex-valued functions defined on V×V×?×V (n-copies). By S_n(V) we mean the set of all symmetric members of T_n(V). We extend the inner product, 〈·,·〉, on V to T_n(V) in the usual way, and we define multiple tensor products A₁⊗A₂⊗?⊗A_n and symmetric products A₁·A₂?A_n, where q₁,q₂,…,q_n are positive integers and A_i∈T_qi(V) for each i, as expected. If A∈S_n(V), then A^k denotes the symmetric product A·A?A where there are k copies of A. We are concerned with producing the best lower bounds for ‖A^k‖², particularly when n=2. In this case we are able to show that ‖A^k‖² is a symmetric polynomial in the eigenvalues of a positive semi-definite Hermitian matrix, M_A, that is closely related to A. From this we are able to obtain many lower bounds for ‖A^k‖². In particular, we are able to show that if ω denotes 1/r where r is the rank of M_A, and , then

     

Lower bound for the oracle projection posterior convergence rate

In Babenko and Belitser (2010), a new notion for the posterior concentration rate is proposed, the so-called oracle risk rate, the best possible rate over an appropriately chosen estimators family, which is a local quantity (as compared, e.g., with global minimax rates). The program of oracle estimation and Bayes oracle posterior optimality is fully implemented in the above paper for the Gaussian white noise model and the projection estimators family.In this note, we complement the upper bound results of Babenko and Belitser (2010) on the posterior concentration rate by a lower bound result, namely that the concentration rate of the posterior distribution around the ‘true’ value cannot be faster than the oracle projection rate.