Jon was exceptionally bright in mathematics and beyond. In mathematics, I am aware of (and greatly impressed by) his passion for and achievements in experimental mathematics, computational number theory and other areas, but I belong to another region within the broad spectrum of Jon’s interests: optimisation and variational analysis. Here Jon has been a recognized world leader for decades. I first emailed Jon with a question regarding his celebrated smooth variational principle about 20 years ago without really expecting him to reply. (Fortunately he did.) Just this result alone published 29 years ago and named after him and his co-author David Preiss would be enough for Jon’s name to be imprinted in history of variational analysis. Jon has always been good at identifying and attacking key problems and concepts as well as providing appropriate names which quickly become common. Metric regularity of set-valued mappings (1986) and linear regularity of collections of sets (jointly with Heinz Bauschke, 1993) are well known examples.
Jon’s coming to Australia in 2009 immediately changed Australian mathematical geography making Newcastle one of the main centres overall and no. 1 in optimisation and variational analysis (and possibly other areas of Jon’s interests). The Priority Research Centre for Computer-Assisted Research Mathematics and its Applications (CARMA) founded by Jon became the recognized leader in optimisation research in Australia and a strong attraction point for researchers worldwide. I wish it will be able to keep this demanding role, although Jon is obviously irreplaceable.
Before CARMA, there was CECM – Centre for Experimental and Constructive Mathematics at Simon Fraser University in Canada – another centre founded by Jon. For many years, without access to journals, CECM preprints were the main source of mathematical optimisation information for me and possibly dozens (or hundreds?) of researchers worldwide.
I share many memories and most of the feelings expressed by the others on this web site. We all miss Jon and will remember his passion for mathematics, incredible intellect, seemingly boundless energy, readiness and willingness to help.
Australian mathematics is in mourning.
[Alexander Kruger, Research Director, Centre for Informatics and Applied Optimisation, Federation University Australia]