Dalmau, VíctorKrokhin, AndreiLarose, Benoit2019-01-212019-01-212008Dalmau V, Krokhin A, Larose B. Retractions onto series-parallel posets. Discrete Math. 2008 Jun 6;308(11):2104-14. DOI: 10.1016/j.disc.2006.08.0100012-365Xhttp://hdl.handle.net/10230/36343The poset retraction problem for a poset P is whether a given poset Q containing P as a subposet admits a retraction onto P, that is, whether there is a homomorphism from Q onto P which fixes every element of P. We study this problem for finite series-parallel posets . We present equivalent combinatorial, algebraic, and topological charaterisations of posets for which the problem is tractable, and, for such a poset P , we describe posets admitting a retraction onto P.application/pdfeng© Elsevier http://dx.doi.org/10.1016/j.disc.2006.08.010info:eu-repo/semantics/articlehttp://dx.doi.org/10.1016/j.disc.2006.08.010Poset retractionSeries-parallelPosetsComplexityinfo:eu-repo/semantics/openAccess