Abstract: Kazhdan and Lusztig constructed Kazhdan-Lusztig polynomials as an application of intersection cohomology theory of Deligne-Goresky-MacPherson for the rational smoothness of Schubert varieties in the flag variety in the late 70s. The rational smoothness from cohomological criteria is a weaker notion of smoothness. There have been the known characterizations of Kazhdan-Lusztig polynomial, Poincare polynomials for Schubert varieties in a projective homogeneous space due to Lascoux- Sch\"{u}tzenberger, Boe, Zelevenski, Sankaran and Vanchinathan. We conjecture analogue ones for (co)vexillary Schubert varieties and discuss how the proof is supposed to go, based on the method by Anderson, Ikeda, Jeon and Kawago. Please email Colleen at cer2 (at) illinois (dot) edu for the Zoom ID and password.