Online Algorithms
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Recent papers in Online Algorithms
In this paper, a new variant of the standard knapsack problem is investigated and applied in cognitive radio networks. More specifically, the centralized spectrum allocation in cognitive radio networks is formulated as a multiple... more
In this work we show how to use efficient online trading algorithms to price the current value of financial instruments, such as an option. We derive both upper and lower bounds for pricing an option, using online trading algorithms. Our... more
ABSTRACT Consider the following problem of serving impatient users: we are given a set of customers we would like to serve. We can serve at most one customer in each time step (getting value vi for serving customer i). At the end of each... more
Graph coloring is the assignment of colors to the graph vertices and edges in the graph theory. We can divide the graph coloring in two types. The first is vertex coloring and the second is edge coloring. The condition which we follow in... more
It has recently been proposed that Internet energy costs, both monetary and environmental, can be reduced by exploiting temporal variations and shifting processing to data centers located in regions where energy currently has low cost.... more
In this work we show how to use efficient online trading algorithms to price the current value of financial instruments, such as an option. We derive both upper and lower bounds for pricing an option, using online trading algorithms. Our... more
We consider a general class of scheduling problems where a set of dependent jobs needs to be scheduled (preemptively or non-preemptively) on a set of machines so as to minimize the weighted sum of completion times. The dependencies among... more
We consider a track assignment problem in a train depot leading to an online bounded coloring problem on permutation graphs or on overlap graphs. For permutation graphs we study the competitiveness of a First Fit-based algorithm and we... more
This chapter surveys results in the design and analysis of self-organizing data structures for the search problem. The general search problem in pointer data structures can be phrased as follows. The elements of a set are stored in a... more
Renewable and distributed energy sources are today possible but these technologies bring benefits as well as challenges, such as their intermittent nature, that leads to utilization problems for the power grid. On the other hand, upcoming... more
Unfair metrical task systems are a generalization of online metrical task systems. In this paper we introduce new techniques to combine algorithms for unfair metrical task systems and apply these techniques to obtain improved randomized... more
We consider the following problem of scheduling with conflicts (SWC): Find a minimum makespan schedule on identical machines where conflicting jobs cannot be scheduled concurrently. We study the problem when conflicts between jobs are... more
Agents that solve problems in unknown graphs are usually required to iteratively explore parts of the graph. In this paper we research the problem of finding a k-clique in an unknown graph while minimizing the number of required... more
The Reverse Greedy algorithm (RGREEDY) for the k-median problem works as follows. It starts by placing facilities on all nodes. At each step, it removes a facility to minimize the total distance to the remaining facilities. It stops when... more
Graph coloring is the assignment of colors to the graph vertices and edges in the graph theory. We can divide the graph coloring in two types. The first is vertex coloring and the second is edge coloring. The condition which we follow in... more
We consider the problem of scheduling a sequence of packets over a linear network, where every packet has a source and a target, as well as a release time and a deadline by which it must arrive at its target. The model we consider is... more
We study the online version of the scheduling problem involving selfish agents considered by Archer and Tardos [FOCS 2001]: jobs must be scheduled on m parallel related machines, each of them owned by a different selfish agent.
Suppose that a program makes a sequence of m accesses (references) to data blocks; the cache can hold k<m blocks. An access to a block in the cache incurs one time unit, and fetching a missing block incurs d time units. A fetch of a new... more
modify the algorithm proposed by Alpern et al. for maintaining the topological order of the n nodes of a directed acyclic graph while inserting m edges and prove that their algorithm runs in O(min{m 3/2 log n, m 3/2 + n 2 log n}) time and... more
Recently network virtualization has been proposed as a promising way to overcome the current ossification of the Internet by allowing multiple heterogeneous virtual networks (VNs) to coexist on a shared infrastructure. A major challenge... more
Given a universe U of n elements and a weighted collection S of m subsets of U, the universal set cover problem is to a-priori map each element u ∈ U to a set S(u) ∈ S containing u, so that X ⊆ U is covered by S(X) = ∪ u∈X S(u). The aim... more
We study packet buffering, a basic problem occurring in network switches. We construct an optimal 16/13-competitive randomized online algorithm PB for the case of two input buffers of arbitrary sizes. Our proof is based on geometrical... more
Given a set S of points in a metric space, and a diver- sity measure div(·) defined over subsets of S, the goal of the diversity maximization problem is to find a sub- set T ⊆ S of size k that maximizes div(T). Motivated by applications in... more
In this paper, we introduce a new online algorithm for orthogonal regression. The method is constructed via an stochastic gradient descent approach combined with the idea of a tube loss function, which is similar to the one used in... more
Given a set S of points in a metric space, and a diversity measure div( ) dened over subsets of S, the goal of the diversity maximization problem is to nd a subset T S of size k that maximizes div(T ). Motivated by applications in massive... more
We consider several online scheduling problems that arise when customers request make-to-order products from a company. At the time of the order, the company must quote a due date to the customer. To satisfy the customer, the company must... more
ABSTRACT In this paper, we study the design and analysis of online batching systems, which can be used to model many popular IT systems such as the Video-On-Demand system and the Pull-based Data Dissemination system. We analyze how the... more
We consider an online version of the conflict-free coloring of a set of points on the line, where each newly inserted point must be assigned a color upon insertion, and at all times the coloring has to be conflict-free, in the sense that... more
We consider the online linear programming problem where the constraint matrix is revealed column by column along with the objective function. We provide a 1−o(1) competitive algorithm for this surprisingly general class of online problems... more
We present an extension of a classical data management subproblem, the page migration. The problem is investigated in dynamic networks, where costs of communication between different nodes may change with time. We construct asymptotically... more
We generalize the classical cow-path problem [7, 14, 38, 39] into a question that is relevant for collective foraging in animal groups. Specifically, we consider a setting in which k identical (probabilistic) agents, initially placed at... more
Online search is a basic online problem. The fact that its optimal deterministic/randomized solutions are given by simple formulas (however with difficult analysis) makes the problem attractive as a target to which other practical online... more
We introduce a data stream model of computation for Graph Drawing, where a source produces a graph one edge at a time. When an edge is produced, it is immediately drawn and its drawing can not be altered. The drawing has an image... more
Given a universe U of n elements and a weighted collection S of m subsets of U, the universal set cover problem is to a-priori map each element u ∈ U to a set S(u) ∈ S containing u, so that X ⊆ U is covered by S(X) = ∪ u∈X S(u). The aim... more
Given a universe U of n elements and a weighted collection S of m subsets of U, the universal set cover problem is to a-priori map each element u ∈ U to a set S(u) ∈ S containing u, so that X ⊆ U is covered by S(X) = ∪ u∈X S(u). The aim... more
Prefetching and caching are widely used for improving the performance of le systems. Recent studies have shown that it is important to integrate the two. In this model we consider the following problem. Suppose that a program makes a... more
The rule-based approach from traditional AI and the conventional constraint satisfaction algorithms are not adequate to cope with the unpredictable events and interactive computations in distributed CAD environments. This paper claims... more
We study the problem of optimally allocating online advertisement space to budget-constrained advertisers. This problem was defined and studied from the perspective of worst-case online competitive analysis by Mehta et al. Our objective... more