We construct an example of a piecewise positive (a.e.) Jacobian such that the usual convolution does not preserve the sign
of the Jacobian. Bibliography:
4 titles.
Dedicated to N. N. Uraltseva on her jubilee
Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 221, 1995, pp. 235–243.
Translated by G. A. Seregin and T. N. Shilkin.