| ⊦ frag*(Π(IOAut(lstart, lstep, lext), IOAut(rstart, rstep, rext), lren, rren))(psl, pal) ∧ n + 1 < # πrs(lstep, rstep, lren, rren, psl, pal) → rstep(πrs(lstep, rstep, lren, rren, psl, pal)[n], πra(lstep, rstep, lren, rren, psl, pal)[n], πrs(lstep, rstep, lren, rren, psl, pal)[n + 1]) |