Steve Jackson (full name: Stephen Craig Jackson) is an American

set theorist Set theory is the branch of mathematical logic that studies sets, which can be informally described as collections of objects. Although objects of any kind can be collected into a set, set theory, as a branch of mathematics, is mostly concern ...

at the

University of North Texas The University of North Texas (UNT) is a public research university in Denton, Texas. It was founded as a nonsectarian, coeducational, private teachers college in 1890 and was formally adopted by the state 11 years later."Denton Normal Schoo ...

. Much of his most notable work has involved the descriptive set-theoretic consequences of the

axiom of determinacy In mathematics, the axiom of determinacy (abbreviated as AD) is a possible axiom for set theory introduced by Jan Mycielski and Hugo Steinhaus in 1962. It refers to certain two-person topological games of length ω. AD states that every game o ...

. In particular he is known for having calculated the values of all the projective ordinals (the

suprema In mathematics, the infimum (abbreviated inf; plural infima) of a subset S of a partially ordered set P is a greatest element in P that is less than or equal to each element of S, if such an element exists. Consequently, the term ''greatest low ...

of the lengths of all prewellorderings of the

real number In mathematics, a real number is a number that can be used to measurement, measure a ''continuous'' one-dimensional quantity such as a distance, time, duration or temperature. Here, ''continuous'' means that values can have arbitrarily small var ...

s at a particular level in the projective hierarchy) under the assumption that the axiom of determinacy holds. In recent years he has also made contributions to the theory of Borel equivalence relations. With

Dan Mauldin Dan or DAN may refer to: People * Dan (name), including a list of people with the name ** Dan (king), several kings of Denmark * Dan people, an ethnic group located in West Africa **Dan language, a Mande language spoken primarily in Côte d'Ivoir ...

he solved the

Steinhaus lattice problem Steinhaus may refer to: *Bibiana Steinhaus, German football referee * Edward Arthur Steinhaus (1914–1969), American insect pathologist * Hugo Steinhaus, mathematician * Steinhaus, Austria, a municipality in Upper Austria, Austria * Steinhaus, ...

. Jackson earned his PhD in 1983 at

UCLA The University of California, Los Angeles (UCLA) is a public university, public Land-grant university, land-grant research university in Los Angeles, California. UCLA's academic roots were established in 1881 as a Normal school, teachers colle ...

under the direction of Donald A. Martin, with a dissertation on ''A Calculation of'' δ¹₅. In it, he proved that, under the axiom of determinacy,

\mathbf=\aleph_

thereby solving the first Victoria Delfino problem, one of the notorious problems of the combinatorics of the

References

External links

List of papers published by Steve Jackson
* University of California, Los Angeles alumni University of North Texas faculty 20th-century American mathematicians 21st-century American mathematicians Living people Year of birth missing (living people) Set theorists {{US-mathematician-stub