https://pages.uoregon.edu/lipshitz/bfh/further/index.html Relative gradings and spinc structures bfh_python computes the decomposition of HF-hat into spinc-structures and the relative Maslov grading in each spinc-structure. It also computes the relative, rational Maslov grading between torsion spinc-structures, and the ambiguity of the Maslov grading in non-torsion spinc-structures (the divisibility of the first Chern class). A lens space from dstructure import infTypeD, zeroTypeD from pmc import splitPMC from arcslide import Arcslide from arcslideda import ArcslideDA Z = splitPMC(1) solid_torus = infTypeD(1) tau_m = ArcslideDA(Arcslide(Z,1,2)) tau_l = ArcslideDA(Arcslide(Z,2,1)) slides = [tau_m, tau_m, tau_l, tau_l] for s in slides: solid_torus = s.tensorD(solid_torus) oth_side = zeroTypeD(1) cf = oth_side.morToD(solid_torus) cf.simplify() print(len(cf)) To get the relative gradings: Hugo en-us lipshitz@uoregon.edu (Robert Lipshitz) lipshitz@uoregon.edu (Robert Lipshitz)