The fractional calculus of variations, with functionals dependent on fractional derivatives and integrals, has experienced a huge development in the last few years due to its many applications in several different areas [22]. Despite the quite vast …

We would like to thank Richard Brito and Vitor Cardoso for a fruitful collaboration on Proca stars. We also thank J. Rosa, M. Sampaio and M. Wang for discussions on Proca fields. C. H. and E. R. acknowledge funding from the FCT-IF programme. H.R. is…

Stepwise refinement of algebraic specifications is a well known formal methodology for program development. However, traditional notions of refinement based on signature morphisms are often too rigid to capture a number of relevant transformations i…

Our main objective is to establish a necessary optimality condition for problems of the calculus of variations with higher-order nabla derivatives. We formulate the higher-order variational problem with nabla derivatives as follows:

In his 1969 paper [19] Massey shows that the Berlekamp-Massey algorithm is an efficient algorithm that yields a parametrization of all shortest feedback shift registers for a given finite sequence S1,…,SN of numbers in a field. The main contribution…