CSASC is a joint meeting of the Czech, Slovenian, Austrian, Slovak and Catalan mathematical societies which started in Prague in 2010 out of former bilateral meetings of the Czech and Catalan societies, and was held in Krems (Austria) in 2011 and Koper (Slovenia) in 2013. This fourth edition in Barcelona displays the continuing lively relationship among the mathematicians from the five societies within the network of multilateral meetings in the EMS.