The isoperimetric profile of a graph is a function that measures, for an integer k, the size of the smallest edge boundary over all sets of vertices of size k. We observe a connection between isoperimetric profiles and computational complexity. We illustrate this connection by an example from communication complexity, but our main result is in algebraic complexity. We prove a sharp super-polyno...

This paper describes the prototype system of a secure shell proxy intrusion detection system (called EPIDS) that controls SSH-connections between clients and servers. EPIDS is a transparent proxy which makes use of a man in the middle attack. Every connection between client and server is decrypted, inspected and encrypted again. If the system finds some unusual behavior it is able to close the ...

In this paper, we propose a multicast protocol for a multihop, mobile wireless network with cluster based routing and token access protocol within each cluster. The multicast protocol uses a shared tree which is dynamically updated to adjust to changes in topology and membership (i.e. dynamic joins and quits). Two options for tree maintenance have been simulated and evaluated: "hard state" (i.e...

Recently a new connection between proof theory and formal language theory was introduced. It was shown that the operation of cut elimination for proofs in first-order predicate logic involving Π1-cuts corresponds to computing the language of a particular class of regular tree grammars. The present paper expands this connection to the level of Π2-cuts. Given a proof π of a Σ1 formula with cuts o...

Inference in Markov random fields, and development and evaluation of similarity measures for nodes in graphs, are both active areas of data-mining research. In this paper, we demonstrate a formal connection between inference in tree-structured Markov random fields and personalized PageRank, a widely-used similarity measure for graph nodes based on graphwalks. In particular we show a connection ...

Routing and wavelength assignment for online real-time multicast connection setup is a difficult task due to the dynamic change of availabilities of wavelengths and the consideration of wavelength conversion delay in wavelength division multiplexing (WDM) networks. This paper presents a distributed routing and wavelength assignment scheme for the setup of real-time multicast connections. It int...

We describe in this paper a connection between bifix codes, symbolic dynamical systems and free groups. This is in the spirit of the connection established previously for the symbolic systems corresponding to Sturmian words. We introduce a class of sets of factors of an infinite word with linear factor complexity containing Sturmian sets and regular interval exchange sets, namely the class of t...

In the admission control problem we are given a network and a set of connection requests, each of which is associated with a path, a time interval, a bandwidth requirement, and a weight. A feasible schedule is a set of connection requests such that at any given time, the total bandwidth requirement on every link in the network is at most 1. Our goal is to find a feasible schedule with maximum t...

In this paper, we introduce a new problem called Tree-Residue Vertex-Breaking (TRVB): given a multigraph G some of whose vertices are marked “breakable,” is it possible to convert G into a tree via a sequence of “vertex-breaking” operations (replacing a degree-k breakable vertex by k degree-1 vertices, disconnecting the k incident edges)? We characterize the computational complexity of TRVB wit...