Emergency-vehicle drivers who aim to reach their destinations through the fastest possible routes cannot rely solely on expected average travel times. Instead, the drivers should combine this travel-time information with the characteristics of data variation and then select the best or optimal route. The problem can be formulated on a graph in which the origin point and destination point are gi...

Mobile agents are autonomous programs that may be dispatched through computer networks. Using a mobile agent is a potentially efficient method to perform transactions and retrieve information in networks. Unknown congestion in a network causes uncertainty in the routing times of mobile agents so the routing of mobile agents cannot rely solely on the average travel time. In this paper we deal wi...

The research community has witnessed a large interest in monitoring large scale distributed systems. In these applications typically we wish to monitor a global system condition which is defined as a function of local network elements parameters. In this paper, we address Aggregate Threshold Queries in sensor networks, which are used to detect when an aggregate value of all sensor measurements ...

The problem of maximizing the weighted number of just-in-time jobs in a two-machine ‡ow shop scheduling system is known to be NP-hard [4]. However, the question of whether this problem is strongly or ordinary NP-hard remains an open question. We provide a pseudo-polynomial time algorithm to solve this problem, proving that it is NP-hard in the ordinary sense. Moreover, we show how the pseudo-po...

We consider the problem of minimizing a class of quasi-concave functions over a convex set. Quasiconcave functions are a generalization of concave functions and thus, NP-hard to minimize over a convex set in general. We present a simple fully polynomial time approximation scheme (FPTAS) for minimizing a fairly general class of low-rank quasi-concave functions. Our algorithm is based on solving ...

We consider a class of optimization problems called movement minimization on euclidean plane. Given a set of nodes on the plane, the aim is to achieve some specific property by minimum movement of the nodes. We consider two specific properties, namely the connectivity (Con) and realization of a given topology (Topol). By minimum movement, we mean either the sum of all movements (Sum) or the max...

Effective enforcement of laws and policies requires expending resources to prevent and detect offenders, as well as appropriate punishment schemes to deter violators. In particular, enforcement of privacy laws and policies in modern organizations that hold large volumes of personal information (e.g., hospitals, banks, and Web services providers) relies heavily on internal audit mechanisms. We s...

We consider a job shop scheduling problem with n jobs and the constraint that at most p < n jobs can be processed simultaneously. This model arises in several manufacturing processes, where each operation has to be assisted by one human operator and there are p (versatile) operators. The problem is binary NP-hard even with n = 3 and p = 2. When the number of jobs is fixed, we give a pseudopolyn...

Understanding the interactions between different combinatorial optimisation problems in real-world applications is a challenging task. Recently, the traveling thief problem (TTP), as a combination of the classical traveling salesperson problem and the knapsack problem, has been introduced to study these interactions in a systematic way. We investigate the underlying non-linear packing while tra...

1 Background In the previous lecture we saw a PTAS for the problem PkM 2 i. Recall that M i is the completion time of machine i. In this lecture we present a PTAS for the problem Pk P c j w j , due to Skutella and Woeginger (1999). Some known results for related problems: 1k P w j c j-can be solved in polynomial time using Smith's Ratio Rule. Pk P c j-can be solved in polynomial time using SPT ...