In this paper, some nice extension properties of a PL $R^\infty$-manifold will be investigated. As a consequence, a homotopy extension theorem for a fiber-preserving piecewise linear $\mu$-homotopy will be proved.
"Homotopy Extension Theorem for a Fiber-Preserving Piecewise Linear $\mu$-Homotopy." Missouri J. Math. Sci. 3 (1) 33 - 42, Winter 1991. https://doi.org/10.35834/1991/0301033