Konstantinos Panagiotou

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In the last decades, the study of models for large real-world networks has been a very popular and active area of research. A reasonable model should not only replicate all the structural properties that are observed in real world networks (for example, heavy tailed degree distributions, high clustering and small diameter), but it should also be amenable to(More)
We analyze the popular push-pull protocol for spreading a rumor in networks. Initially, a single node knows of a rumor. In each succeeding round, every node chooses a random neighbor, and the two nodes share the rumor if one of them is already aware of it. We present the first theoretical analysis of this protocol on random graphs that have a power law(More)
In the k-search problem, a player is searching for the k highest (respectively, lowest) prices in a sequence, which is revealed to her sequentially. At each quotation, the player has to decide immediately whether to accept the price or not. Using the competitive ratio as a performance measure, we give optimal deterministic and randomized algorithms for both(More)
Let <i>C</i> be a class of labeled connected graphs, and let C<sub><i>n</i></sub> be a graph drawn uniformly at random from graphs in <i>C</i> that contain exactly <i>n</i> vertices. Denote by <i>b</i>(&ell;; C<sub><i>n</i></sub>) the number of blocks (i.e., maximal biconnected subgraphs) of C<sub><i>n</i></sub> that contain exactly &ell; vertices, and let(More)
Broadcasting algorithms are important building blocks of distributed systems. In this work we investigate the typical performance of the classical and well-studied push model. Assume that initially one node in a given network holds some piece of information. In each round, every one of the informed nodes chooses independently a neighbor uniformly at random(More)
A class A of graphs is called weakly addable (or bridge-addable) if for any G ∈ A and any two distinct components C1 and C2 in G, any graph that can be obtained by adding an edge between C1 and C2 is also in A. McDiarmid, Steger and Welsh conjectured in [6] that a graph chosen uniformly at random among all graphs with n vertices in a weakly addable A is(More)
In the past decades the <i>G</i><sub><i>n,p</i></sub> model of random graphs, introduced by Erd&#337;s and R&#233;nyi in the 60's, has led to numerous beautiful and deep theorems. A key feature that is used in basically all proofs is that edges in <i>G</i><sub><i>n,p</i></sub> appear independently. The independence of the edges allows, for example, to(More)
The paradigm of many choices has influenced significantly the design of efficient data structures and, most notably, hash tables. Cuckoo hashing is a technique that extends this concept. There, we are given a table with n locations, and we assume that each location can hold one item. Each item to be inserted chooses randomly k ≥ 2 locations and has to be(More)
Random <i>k</i>-SAT is the single most intensely studied example of a random constraint satisfaction problem. But despite substantial progress over the past decade, the threshold for the existence of satisfying assignments is not known precisely for any k&#8805;3. The best current results, based on the second moment method, yield upper and lower bounds that(More)