A survey on applications of a new approach to Quillen rational homotopy theory -- The Yang problem for complete bounded complex submanifolds a survey -- Orthogonal polynomials and operator theory -- Open problems and applications -- A Sample of problems where ULRICH BUNDLES show up.

The book contains a selection of research and expository papers in pure and applied mathematics presented by various authors as plenary or invited speakers at the biennial congress of the Spanish Royal Mathematical Society held in Ciudad Real (Spain) in January 2022. The main results focus on the Yang problem and its solution proposed by Globevnik; a phylogenetic reconstruction based on algebra; the Calderon problem for local and nonlocal Schrödinger equations; some open problems in orthogonal polynomial theory; Quillen’s rational homotopy theory; Ulrich bundles and applications; and free objects in theory of Banach spaces. Researchers in these fields are potential audiences.