Hein, Nickolas; Sottile, Frank; Zelenko, Igor A congruence modulo four for real Schubert calculus with isotropic flags. (English) Zbl 1368.14065 Can. Math. Bull. 60, No. 2, 309-318 (2017). Summary: We previously obtained a congruence modulo four for the number of real solutions to many Schubert problems on a square Grassmannian given by osculating flags [N. Hein et al., J. Reine Angew. Math. 714, 151–174 (2016; Zbl 1403.14088)]. Here, we consider Schubert problems given by more general isotropic flags, and prove this congruence modulo four for the largest class of Schubert problems that could be expected to exhibit this congruence. Cited in 1 Document MSC: 14N15 Classical problems, Schubert calculus 14P10 Semialgebraic sets and related spaces Keywords:Lagrangian Grassmannian; Wronski map; Shapiro conjecture Citations:Zbl 1403.14088 PDFBibTeX XMLCite \textit{N. Hein} et al., Can. Math. Bull. 60, No. 2, 309--318 (2017; Zbl 1368.14065) Full Text: DOI arXiv