"Recreational Mathematics" is a problematic expression. For some people, like most professional mathematicians, Mathematics is lots of fun; but for others, like some students, Mathematics can be a nightmare.
Historically, we know that some mathematical research areas are deeply linked to puzzles and games : probability and chance games, graph theory and the Brigdes of Königsberg come to mind.
Ludus Association, the Portuguese Mathematical Society, Centro Interuniversitário de História das Ciências e da Tecnologia (CIUHCT), and Ciência Viva will organize the Recreational Mathematics Colloquium IV.
Museu Nacional de História Natural e da Ciência will be our host.
Our Colloquium will be a Show and Tell of bright pearls of Mathematics, with varied levels of sophistication, entertaining many audiences. Its main goal is to foster mathematical appreciation, an important step if we are to see improvements in the future generations.