The Pansu conjecture asserts that the Pansu balls minimize horizontal perimeter among measurable sets of fixed volume in the first Heisenberg group.
Chen et al. (2026) reported the unrestricted sharp isoperimetric inequality
for
and finite horizontal perimeter
, with equality iff
agrees with a Pansu
ball except on a set of measure zero. Here
is Lebesgue
measure in the coordinates and normalization
used in the definition of a Pansu ball.