We provide two new, simple proofs of Afriat’s celebrated theorem stating that a finite set of price-quantity observations is consistent with utility maximization if, and only if, the observations satisfy a variation of the Strong Axiom of Revealed Preference known as the Generalized Axiom of Revealed Preference. CitationTechnical Report No. 1381, School of Operations Research … Read more
The introduction of digital technology all over Europe requires a complete and challenging re-planning of the actual terrestrial broadcasting system. In fact, in order to implement digital networks, transmitters and frequencies must be removed from the current analog networks. On the other hand, the service level (territory coverage) of analog networks must be preserved until … Read more
We generalize new criss-cross type algorithms for linear complementarity problems (LCPs) given with sufficient matrices. Most LCP solvers require apriori information about the input matrix. The sufficiency of a matrix is hard to be checked (no polynomial time method is known). Our algorithm is similar to Zhang’s linear programming, and Akkeleº-Balogh-Illés’s criss-cross type algorithm for … Read more
We show that a simple genralization of the Deferred Acceptance Procedure with men proposing due to Gale and Shapley(1962), yeilds outcomes for a generalized marriage problem, which are necessarily stable. We also show, that any outcome of this prcedure is Weakly Pareto Optimal for Men, i.e., there is no other outcome which all men prefer … Read more
Many oil wells in Brazilian onshore fields rely on artificial lift methods. Maintenance services such as cleaning, reinstatement, stimulation and others are essential to these wells. These services are performed by workover rigs, which are avaliable on a limited number with respect to the number of wells demanding service. The decision of which workover rig … Read more
We consider the problem of scheduling hypermedia documents with elastic times. The objects have variable durations characterized by ideal, minimum, and maximum values. A schedule is a set of tensions on the arcs of the precedence graph which also represents synchronization constraints. We consider the problem of deciding if there exists a schedule in which … Read more
We consider the problem of scheduling a set of tasks related by precedence constraints to a set of processors, so as to minimize their makespan. Each task has to be assigned to a unique processor and no preemption is allowed. A new integer programming formulation of the problem is given and strong valid inequalities are … Read more
The problem of automatic scheduling hypermedia documents consists in finding the optimal starting times and durations of objects to be presented, to ensure spatial and temporal consistency of a presentation while respecting limits on shrinking and stretching the ideal duration of each object. The combinatorial nature of the minimization of the number of objects whose … Read more
Football is the most followed and practiced sport in Brazil, with a major economic importance. Thousands of jobs depend directly from the activity of the football teams. The Brazilian national football championship is followed by millions of people, who attend the games in the stades, follow radio and TV transmissions, and check newspapers, radio, TV, … Read more
We consider the scheduling problem of minimizing the average weighted completion time on identical parallel machines when jobs are arriving over time. For both the preemptive and the nonpreemptive setting, we show that straightforward extensions of Smith’s ratio rule yield smaller competitive ratios than the previously best-known deterministic on-line algorithms. CitationWorking Paper 4435-03, Sloan School … Read more