2022 Edition

Operational Research in Seaside Operations under Uncertainty

14h15 - 15h15

Filipe Rodrigues [frodrigues@iseg.ulisboa.pt]  

Abstract: Operational Research has a wide range of real-world applications. This talk is about one of them: seaside operations. Seaside operations play a critical role in the world; however, they are highly affected by several uncertain factors like weather conditions and mechanical failures of equipment. Therefore, to obtain solutions applied in practice, it is essential to take such uncertainty into account when designing solution methods. This talk focuses on two different problems arising in seaside operations: the maritime inventory routing problem and the berth allocation problem. For both problems, several approaches to handle uncertainty are overviewed, namely: stochastic programming, robust optimization, and risk-measures. The benefits of operational research – in particular, the use of tools to deal with uncertainty – are shown by the computational results. 

 Black holes or the unbearable curvatureness of being

15h35 - 15h55

Ivo Sengo [sengo@ua.pt]

Abstract: In 1915 Einstein published its theory of General Relativity, which is still the most trustworthy theory that we have for the description of all gravitational phenomena. Although mathematically elegant,  this theory predicts its own demise: Einstein's equations inform us that from the collapse of very massive stars a black hole must emerge and, inside it, a singularity in the geometry of the spacetime. Black holes are characterized for having an event horizon: a region in the spacetime from which nothing can escape, not even light. For many decades such objects belonged to the realm of mathematics but today, more than a century after the discovery of the Schwarzschild metric, we can not only hear them, through the waves that they generate when colliding, but  we can also see them. But what does it mean to see an invisible object, and what do we expect to learn from these images? And, more importantly, do these black holes have hair?

Sharp bounds on the least eigenvalue of a graph determined from edge clique partitions

16h50 - 17h10

Inês Serôdio Costa [inesserodiocosta@ua.pt]  

Abstract: In this talk, sharp bounds on the least eigenvalue of an arbitrary graph are presented. Necessary and sufficient (just sufficient) conditions for the lower (upper) bound to be attained are deduced using edge clique partitions. As an application, we prove that the least eigenvalue of the n-Queens' graph is equal to -4 for every n>3 and it is also proven that its multiplicity is (n-3)2.