## In Memoriam Barry Cooper

Prof. Barry Cooper, Doctor Honoris Causa of Sofia University “St. Clement of Ochrid” suddenly passed away on 26 October 2015. He was one of the leading professors at the University of Leeds Logic Group and a good friend of the logicians from Sofia.

He was born in 1943, graduated in 1966 from Oxford University, and in 1971 received his doctorate from the University of Manchester. In 1969 he began teaching at the University of Leeds and in 1996 he became Professor there. In 2011 he was awarded Doctor Honoris Causa by Sofia University “St. Clement of Ochrid”. His interests were in Computability Theory (more precisely Incomputability) and in particular in the theory of Degrees of Solvability, he was one of the pioneers in field of the Enumeration Degrees. He was very popular among the students and a charismatic lecturer. He instructed many postgraduate student, even now he has left six behind.

Barry Cooper first visited Bulgaria in 1988, during the second Logic Biennale “Heyting’88”. In 2002 he founded the research network “Computability in Europe” (CiE), a node in which is the Department of Mathematical Logic and Applications FMI, SU. In 2008, this network grew into an association. Since 2005 it organizes the annual CiE conference. In 2011 the conference was hosted by Sofia University and Barry Cooper was an invited lecturer.

Barry Cooper loved Bulgaria and often come to visit. His last scientific visit was in 2014 in Gyulechitsa, where the Sofia Logic Group held a conference in memory of Ivan Soskov.

Prof. Cooper had a main role in the European network “MathLogAps” – a graduate program for students in the field of mathematical logic and its applications funded by the European Commission, with the support of which three young Bulgarians completed their doctoral degrees. Two of them: Mariya Soskova and Trifon Trifonov, are now associate professors at the Faculty of Mathematics and Informatics of the university.

In the past few years Prof. Cooper participated with incredible energy in the organization of a number of events on the occasion of the hundredth anniversary of the birth of Alan Turing. He was one the organizers of the six-month program “Semantics & Syntax” (SAS) at the Isaac Newton Institute of Mathematical Sciences at Cambridge University. Together with Mariya Soskova, he succeeded to bring together many of the famous researchers in Computability Theory for the conference “The Incomputable” in Chicheley Hall. He was the co-chair of the program committee of CiE 2012 in Cambridge. His book, co-edited with Jan van Leeuwen, “Alan Turing: His work and Impact” received the Association of American Publishers “R. R. Hawkins Award”. Another accomplishment was the royal pardon for Turing, the British government apologized for the fate of Turing in 2013. In 2014 the film “The Imitation Game” attracted great interest. All this was achieved thanks to the incredible enthusiasm and work of Prof. Barry Cooper.

Besides mathematics, Barry Cooper loved books, sports, music. In his school years he was in the youth rugby team of England. Running was his hobby and he regularly participated in marathons, the last one being the 2010 London Marathon. He was the founder of the Leeds Jazz Club and he was loved by everyone in it. He was also politically active, as a left-winger he was involved in many political campaigns, including the Chile Solidarity Campaign after the military coup there in 1973.

He was a very fine man with a big heart and a good friend. We will miss him a lot.