Biography:Roy Dyckhoff

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Roy Dyckhoff
Born(1948-03-04)March 4, 1948
DiedAugust 23, 2018(2018-08-23) (aged 70)
Alma materUniversity of Cambridge, (BSc)
University of Oxford (Dr. Phil., 1974)
Spouse(s)
Cecilia Meredith (m. 1970)
Scientific career
FieldsMathematics, Logic, Proof theory
InstitutionsUniversity of St Andrews
ThesisTopics in General Topology: Bicategories, Projective Covers, Perfect Mappings and Resolutions of Sheaves (1974)
Doctoral advisorPeter J. Collins
Dana Scott
Doctoral studentsMuffy Calder[1]

Roy Dyckhoff (March 4, 1948 – August 23, 2018) was a British mathematician, logician and computer scientist who worked in logic and proof theory in the Department of Pure Mathematics and later Computer Science at the University of St Andrews.[2] He is most well known for his discovery in 1992 of a terminating sequent calculus for intuitionistic propositional logic.[3][4] His Erdős number was 3.[5]

Early life and education

Roy Dyckhoff was born on March 4, 1948, in Manchester, to Eric Bernard Charles Dyckhoff, a solicitor, and Muriel Edith Turner. He had an older sister, Elisabeth Mary.[6] His mother died on October 6, 1955, when he was only seven years old. Later remarrying in 1959,[7] his father ran the law firm Dyckhoff and Johnson in Cheadle and founded the Cheadle Civic Society.[8] Eric's collection of London and North Western Railway handbills and correspondences are kept at the John Rylands Research Institute and Library.[9]

Raised in Cheshire, he spent his youth at the prestigious boarding school Winchester College.[10] As a student at Winchester College, Dyckhoff grew an interest in church bell-ringing, joining a group of ringers there.[11] Roy spent a year programming punch-cards at English Electric Leo Marconi.[2] This experience convinced him to pursue a career in academia instead of industry. Enrolling in an undergraduate program at King's College, Cambridge in 1966, he studied Mathematics but also spent a year attending only lectures in Middle Eastern studies.[12] During his time at King's College, he rang a peal at Trumpington with a band of first year students.[11]

After receiving his undergraduate degree, he pursued further studies at New College, Oxford, completing a DPhil in Mathematics in 1974. His dissertation, Topics in General Topology: Bicategories, Projective Covers, Perfect Mappings and Resolutions of Sheaves, was supervised by Peter J. Collins and Dana Scott.[1] He was later appointed Fellow of Magdalen College, Oxford.[12]

Career

In 1975, he became a Lecturer in the Department of Pure Mathematics at St Andrews, later moving to Computer Science in 1981[10] due to the reduced funding under the Thatcher government.[12] Early in his scientific career, he contributed to topology and category theory.[1][13] Applying his experience in programming and interest in formal logic, he shifted to theoretical computer science and logic where he came to specialise in proof theory and automated theorem proving.[12]

His investigations into intuitionistic logic led him to discover the contraction-free intuitionistic sequent calculus G4ip in 1992.[3][14] The contraction rule was known to be problematic for backward proof-searches as it can cause unwanted loops. By producing a contraction-free calculus and proving the admissibility of contraction, Dyckhoff provided the first terminating intuitionistic propositional sequent calculus. Such a calculus was anticipated in 1950s by the founder of the Soviet school of game theory, Nikolai Vorobyov. Dyckhoff's calculus laid the groundwork for subsequent terminating proof systems.[15] Additionally he settled a question posed by Georg Kreisel in 1971 on the relationship between cut-elimination, substitution and normalisation. He co-authored several papers with Sara Negri on topics involving intermediate and modal logics.[12]

His later works investigated Aristotelian and Stoic logic. With Susanne Bobzien he proved the decidability of Stoic logics in a Hertz-Gentzen system.[16]

Personal life

Roy married Cecilia Meredith in 1970,[12] and the couple spent their time between St Andrews and Glengarry, Invergarry in the Scottish Highlands. They had two children: a daughter, Livia, and a son, Max, who later went on to work as engineer for Bungie on Halo 3.[17][18] As a Tower captain at the St Salvator's Chapel, Roy rang for various services, occasionally involving his wife and children in the ringing.[19] He was involved in the installation of additional bells in 2003 and later in 2010 to commemorate the consecration of the chapel and the founding of the university.[11] He was also an avid hiker and bell-ringer in his free time, and supported the Mountain Bothies Association.[10]

Later life and death

Despite worsening health, Dyckhoff continued to support ringing at St Andrews and the Tulloch Ringing Centre in Roybridge.[11] Roy Dyckhoff died on the morning of the 23rd of August 2018, aged 70, from an acute myeloid leukemia.[12][20] He was survived by his daughter Livia and son Max Dyckhoff.[12]

References

  1. ↑ 1.0 1.1 1.2 Roy Dyckhoff at the Mathematics Genealogy Project
  2. ↑ 2.0 2.1 "Dr Roy Dyckhoff: A Eulogy". 13 November 2018. https://blogs.cs.st-andrews.ac.uk/csblog/2018/11/13/dr-roy-dyckhoff-a-eulogy/. 
  3. ↑ 3.0 3.1 Dyckhoff, Roy (1992). "Contraction-free sequent calculi for intuitionistic logic". Journal of Symbolic Logic 57 (3): 795-807. doi:10.2307/2275431. 
  4. ↑ Anne Sjerp Troelstra; Helmut Schwichtenberg (2000). Basic proof theory (2nd ed.). Cambridge University Press. ISBN 978-0-521-77911-1. 
  5. ↑ "Roy Dyckhoff's page at St Andrews". http://rd.host.cs.st-andrews.ac.uk/. 
  6. ↑ "Deaths, Dyckhoff". The Times (London) (66356): col Personal Column, p. 22. 11 November 1998. : "DYCKHOFF - Eric Bernard Charles, Solicitor, of Cheadle, Cheshire. Died peacefully on November 8th. 1998 after a short illness. Widower of Muriel and Jean and loving father of Elisabeth and Roy. Father-in-law of Cecillia, and grandfather of Livia and Max."
  7. ↑ "Marriage 1938 - Eric Dyckhoff & Turner". FreeBMD. ONS. https://www.freebmd.org.uk/cgi/information.pl?cite=64B5dFTLyrvj9C7T52eR9w&scan=1. Retrieved 3 June 2025. 
    "Death 1955 - Muriel Dyckhoff". FreeBMD. ONS. https://www.freebmd.org.uk/cgi/information.pl?cite=FQJQ%2F43M5VQgFYce2Xv53w&scan=1. Retrieved 3 June 2025. 
    "Marriage 1959 - Eric Dyckhoff & Wilson". FreeBMD. ONS. https://www.freebmd.org.uk/cgi/information.pl?cite=XHlbt1QUAHR0cKnPkGyThg&scan=1. Retrieved 2 June 2025. 
  8. ↑ "About Us". https://www.cheadlecivicsociety.uk/about-us. 
  9. ↑ "Eric Dyckhoff collection". http://rylibweb.man.ac.uk/specialcollections/collections/guide/atoz/railway/dyckhoff/. 
  10. ↑ 10.0 10.1 10.2 "Dr Roy Dyckhoff". 4 September 2018. https://blogs.cs.st-andrews.ac.uk/csblog/2018/09/04/dr-roy-dyckhoff/. 
  11. ↑ 11.0 11.1 11.2 11.3 Peter Williamson. "Obituary Roy Dyckhoff". https://www.sacr.org/index.php/association/obituaries/48-obituary-roy-dyckhoff. 
  12. ↑ 12.0 12.1 12.2 12.3 12.4 12.5 12.6 12.7 "Annual Report 2019". https://www.kings.cam.ac.uk/sites/default/files/documents//kings-annual-report-2019-web.pdf. 
  13. ↑ Dyckhoff, Roy; Tholen, Walter (1987). "Exponentiable morphisms, partial products and pullback complements". Journal of Pure and Applied Algebra 49 (1-2): 103-116. doi:10.1016/0022-4049(87)90124-1. 
  14. ↑ Graham-Lengrand, Stephane; Negri, Sara (2019). "Remembering Roy Dyckhoff". 28th International Conference, TABLEAUX 2019. London, UK. pp. xiv--xvii. doi:10.1007/978-3-030-29026-9. https://www.mv.helsinki.fi/home/negri/roy_mem_tableaux.pdf. 
  15. ↑ Iemhoff, Rosalie (2022). "The G4i Analogue of a G3i Sequent Calculus". Studia Logica 110: 1493-1506. doi:10.1007/s11225-022-10008-3. 
  16. ↑ Dyckhoff, Roy; Bobzien, Susanne (2019). "Analyticity, Balance and Non-admissibility of Cut in Stoic Logic". Studia Logica 107: 375-397. doi:10.1007/s11225-018-9797-5. 
  17. ↑ "Roy Dyckhoff's page at the Department of Computer Science at St Andrews". http://rd.host.cs.st-andrews.ac.uk/. 
  18. ↑ Clive Thompson (27 September 2007). "Smart Tweaks Amp Up Halo 3's Killer AI". https://www.wired.com/2007/09/halo-ai/. 
  19. ↑ "2014 Annual Report". https://www.sacr.co.uk/images/documents/annual%20reports/2014%20SACR%20Annual%20Report%20Website.pdf. 
  20. ↑ "ASL Newsletter - January 2019". https://aslonline.org/wp-content/uploads/2019/01/Jan2019newsletter-1.pdf. 



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