Let X be an arcwise connected
Hausdorff space in which the union of any nest of arcs is contained in an arc. Let
f,g : X → X be commuting functions (not necessarily continuous), which satisfy (1)
f(A) and g(A) are arcwise connected for each arc A ⊂ X, and (2) f−1(x) and g−1(x)
are arcwise connected for each x ∈ X. The principal result of this paper
is:
Theorem. The functions f and g have a common fixed point.