Joachim Hyam Rubinstein FAA (born 7 March 1948, in Melbourne) is[update] an Australian top mathematician specialising in low-dimensional topology;[1] he is currently serving as an honorary professor in the Department of Mathematics and Statistics at the University of Melbourne, having retired in 2019.

In 1974, Rubinstein received his Ph.D. from the University of California, Berkeley under the advisership of John Stallings.

His dissertation was on the topic of Isotopies of Incompressible Surfaces in Three Dimensional Manifolds.

[5] His major contributions include results involving almost normal Heegaard splittings and the closely related joint work with Jon T. Pitts relating strongly irreducible Heegaard splittings to minimal surfaces, joint work with William Jaco on special triangulations of 3-manifolds (namely 0-efficient and 1-efficient triangulations), and joint work with Martin Scharlemann on the Rubinstein–Scharlemann graphic.

His research interests also include: shortest networks applied to underground mine design, machine learning, learning theory, financial mathematics, and stock market trading systems.