Peter Tennant Johnstone (born 1948) is Professor of the

Foundations of Mathematics Foundations of mathematics is the study of the philosophy, philosophical and logical and/or algorithmic basis of mathematics, or, in a broader sense, the mathematical investigation of what underlies the philosophical theories concerning the natu ...

at the

University of Cambridge , mottoeng = Literal: From here, light and sacred draughts. Non literal: From this place, we gain enlightenment and precious knowledge. , established = , other_name = The Chancellor, Masters and Schola ...

, and a fellow of St. John's College. He invented or developed a broad range of fundamental ideas in

topos theory In mathematics, a topos (, ; plural topoi or , or toposes) is a category that behaves like the category of sheaves of sets on a topological space (or more generally: on a site). Topoi behave much like the category of sets and possess a notion ...

. His thesis, completed at the University of Cambridge in 1974, was entitled "Some Aspects of

Internal Category In mathematics, more specifically in category theory, internal categories are a generalisation of the notion of small category, and are defined with respect to a fixed ambient category. If the ambient category is taken to be the category of sets the ...

Theory in an

Elementary Topos In mathematics, a topos (, ; plural topoi or , or toposes) is a category that behaves like the category of sheaves of sets on a topological space (or more generally: on a site). Topoi behave much like the category of sets and possess a notion ...

". He is a great-great nephew of the Reverend

George Gilfillan __NOTOC__ Rev George Gilfillan (30 January 1813 – 13 August 1878) was a Scottish author and poet. One of the spasmodic poets, Gilfillan was also an editor and commentator, with memoirs, critical dissertations in many editions of earlier Britis ...

who was eulogised in

William McGonagall William Topaz McGonagall (March 1825 – 29 September 1902) was a Scottish poet of Irish descent. He gained notoriety as an extremely bad poet who exhibited no recognition of, or concern for, his peers' opinions of his work. He wrote about 2 ...

's first poem.

Books

*. :— " r too hard to read, and not for the faint-hearted"An anonymous referee, as quoted by Johnstone in his ''Sketches of an elephant'', p. ix. *. *. * (v.3 in preparation)

References

External links

Johnstone's web page
* * {{DEFAULTSORT:Johnstone, Peter Category theorists Living people Cambridge mathematicians Fellows of St John's College, Cambridge 1948 births