Given a decreasing sequence {aⁿ} of nonnegative terms, we prove that there exist subsequences {nk } of {n} such that ∑k=1∞nk+1−nkank and ∑n=1∞an have the same convergence. In particular, ∑n=1∞an ...

An association between vine habit and cordate leaf shape in higher plants has been reported, but previous comparative analyses have not taken into account phylogenetic history. We surveyed the flora ...