The definitions of the Hausdorff
dimension dimhX, upper metric dimension dimX and lower metric dimension
dimX of a metric space X all depend upon asymptotic characteristics of
diameters of sets in covers of X. We relate these notions. First we note that
dimhX ≤dimX holds for all totally bounded metric spaces X, while on the
other hand there exist perfect subsets A of [0,1] satisfying dimhA = 0 and
dimA = 1 =dim[0,1]. Finally we show that there exist perfect subsets S of [0,1]
which satisfy dimhS = 0 and dimS = 1 even when strong local conditions are
imposed.