Alexander Isaev of the Mathematical Sciences Institute (MSI), Australian National University, passed away at home on Tuesday, 20 August 2019. Alex was a much loved, long standing member of the MSI community. His colleagues greatly admired his intellectual and moral integrity, and his rigorous teaching style.

Born in 1964, Alex grew up in the Soviet Union and studied mathematics at Moscow State University, studying complex analysis under the guidance of Anatoli Georgievich Vitushkin. His master degree was awarded in 1986 and his PhD in 1990.

Alex’s long association with ANU began in 1992, when he took up a postdoctoral position at the Centre for Mathematics and its Applications. He successfully applied for an ARC Fellowship which he held from 1996 to 2001, when he was appointed to an ongoing position.

Part of Alex’s responsibilities on taking up this position included setting up the course offerings in bioinformatics, and this eventually led to his book “Introduction to Mathematical Methods in Bioinformatics’’ which was published in the Springer Universitext series in 2004.

Alex was an influential researcher in complex analysis, producing important results throughout his career. His work centred on the classification of complex spaces according to their symmetries. Early successes included Alex’s work with Steven Krantz in 1999 on classifying complex domains with a non-compact automorphism group, and their subsequent work on automorphisms of hyperbolic manifolds. More recent breakthroughs include his proof with Kruglikov of two important conjectures (the Beloshapka conjecture and the Dimension conjecture) on the symmetry algebras of 5-dimensional CR manifolds (published in 2017). Alex’s work in complex analysis produced two important research monographs: “Lectures on the Automorphism Groups of Kobayashi-Hyperbolic Manifolds’’, in 2007, and “Spherical Tube Hypersurfaces’’, published in 2011, both in the Springer Lecture Notes in Mathematics. He also published the more expository text “Twenty-One Lectures on Complex Analysis, A First Course’’ in 2017.

Alex was remarkable for the fortitude and honesty with which he faced his illness of the past three years. His close colleagues and friends from the MSI were amazed that he was able to come back from what appeared to be a devastating prognosis in 2016, even cycling and walking to work. During his last three years, he found solace in mathematics and produced an absolutely extraordinary body of work, posting 17 articles to the mathematics arXiv in this period.

Alex is survived by his wife Esfir Nikiforova and his daughter Maria.

Alex will be dearly missed by his friends and colleagues in the Mathematical Sciences Institute and across Australia.