[0R9]Topics:distance function.
Show that dA is a Lipschitz function.
Show that dA≡dA―.
Show that {x,dA(x)=0}=A―.
If M=ℝn and A is closed and non-empty, show that the infimum in [(9.62)]↺↻ is a minimum.
See also [198]↺↻ and [19B]↺↻.
[0RB]↺↻