Luís Cavique

The crew timetabling problem: An extension of the crew scheduling problem

In some urban transportation companies driving periods are short when compared with the total duty time, leading to long non-driving periods that can be used as cover time. This paper presents the Crew Timetabling Problem, an extension of the Crew Scheduling Problem in which crew timetables are obtained by levelling the cover crew resources. An objective function for this problem is proposed in order to balance the number of driving and cover crews. A Lisbon Underground case study is used to illustrate the Crew Timetabling Problem. The problem is represented in a multigraph and solved by a tabu search-based heuristic.

Ramex: A Sequence Mining Algorithm Using Poly-trees

Sequence mining combines the discovery of frequent itemsets and the order they appear in. Most of the sequence pattern discovery techniques present some handicaps like the generation of a huge number of rules and the lack of scalability. In this work the proposed algorithm concerns the analysis of the whole rather than the parts, thus providing a holistic view of the sequences. The algorithm analyzes event logs and allows a non-expert user to understand the sequences using a poly-tree visualization. The scalability associated with condensed data structures, which shrink the data without losing information, allows dealing with the Big Data challenge. Ramex was implemented in different scenarios.

Ramex-Forum: Sequential Patterns of Prices in the Petroleum Production Chain

We present a sensibility analysis and new visualizations using an improved version of the Ramex-Forum algorithm applied to the study of the petroleum production chain. Different combinations of parameters and new ways to visualize data will be used. Results will highlight the importance of Ramex-Forum and its proper parameterizations for ana- lyzing relevant relations among price variations in petroleum and other similar markets.