Peter Tennant Johnstone (born 1948) is Professor of the

Foundations of Mathematics Foundations of mathematics is the study of the 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 nature of mathe ...

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 ...

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 not ...

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