A Fixed Point Theorem for Certain Maps on Certain Nonseparating Plane Continua

doi:10.1201/9780203910245-22

ABSTRACT

We write Hl(Y) K 0 to mean that every map of Y to the circle S1 is inessential (i.e., homotopic to a constant map); hence, Hl(Y) ~ 0 means that the first Cech cohomology group of the space Y is trivial (see 8.1 of [D, p. 226]).