Daniel Marinus Kan (or simply Dan Kan) (August 4, 1927 – August 4, 2013) was a Dutch

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History On ...

working in

category theory Category theory is a general theory of mathematical structures and their relations that was introduced by Samuel Eilenberg and Saunders Mac Lane in the middle of the 20th century in their foundational work on algebraic topology. Nowadays, cate ...

and

homotopy theory In mathematics, homotopy theory is a systematic study of situations in which maps can come with homotopies between them. It originated as a topic in algebraic topology but nowadays is studied as an independent discipline. Besides algebraic topolog ...

. He was a prolific contributor to both fields for six decades, having authored or coauthored several dozen research papers and monographs.

Career

He received his

Ph.D. A Doctor of Philosophy (PhD, Ph.D., or DPhil; Latin: or ') is the most common degree at the highest academic level awarded following a course of study. PhDs are awarded for programs across the whole breadth of academic fields. Because it is a ...

Hebrew University The Hebrew University of Jerusalem (HUJI; he, הַאוּנִיבֶרְסִיטָה הַעִבְרִית בִּירוּשָׁלַיִם) is a public research university based in Jerusalem, Israel. Co-founded by Albert Einstein and Dr. Chaim Weiz ...

in 1955, under the direction of

Samuel Eilenberg Samuel Eilenberg (September 30, 1913 – January 30, 1998) was a Polish-American mathematician who co-founded category theory (with Saunders Mac Lane) and homological algebra. Early life and education He was born in Warsaw, Kingdom of Poland to a ...

. His students include Aldridge K. Bousfield, William Dwyer,

Stewart Priddy Stewart may refer to: People *Stewart (name), Scottish surname and given name *Clan Stewart, a Scottish clan *Clan Stewart of Appin, a Scottish clan Places Canada *Stewart, British Columbia *Stewart Township, Nipissing District, Ontario (histor ...

, Emmanuel Dror Farjoun and

Jeffrey H. Smith Jeffrey Henderson Smith is a former professor of mathematics at Purdue University in Lafayette, Indiana. He received his Ph.D. from the Massachusetts Institute of Technology in 1981, under the supervision of Daniel Kan, and was promoted to full pr ...

. He was an emeritus professor at the

Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a private land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern technology and science, and is one of the ...

where he taught from 1959, formally retiring in 1993.

Work

He played a role in the beginnings of modern homotopy theory similar to that of

Saunders Mac Lane Saunders Mac Lane (4 August 1909 – 14 April 2005) was an American mathematician who co-founded category theory with Samuel Eilenberg. Early life and education Mac Lane was born in Norwich, Connecticut, near where his family lived in Taftvill ...

homological algebra Homological algebra is the branch of mathematics that studies homology (mathematics), homology in a general algebraic setting. It is a relatively young discipline, whose origins can be traced to investigations in combinatorial topology (a precurs ...

, namely the adroit and persistent application of categorical methods. His most famous work is the abstract formulation of the discovery of

adjoint functors In mathematics, specifically category theory, adjunction is a relationship that two functors may exhibit, intuitively corresponding to a weak form of equivalence between two related categories. Two functors that stand in this relationship are kno ...

, which dates from 1958. The

Kan extension Kan extensions are universal constructs in category theory, a branch of mathematics. They are closely related to adjoints, but are also related to limits and ends. They are named after Daniel M. Kan, who constructed certain (Kan) extensions us ...

is one of the broadest descriptions of a useful general class of adjunctions. From the mid-1950s he made distinguished contributions to the theory of

simplicial set In mathematics, a simplicial set is an object composed of ''simplices'' in a specific way. Simplicial sets are higher-dimensional generalizations of directed graphs, partially ordered sets and categories. Formally, a simplicial set may be defined a ...

s and simplicial methods in topology in general. In recognition of this, fibrations in the usual

closed model category In mathematics, particularly in homotopy theory, a model category is a category with distinguished classes of morphisms ('arrows') called ' weak equivalences', 'fibrations' and 'cofibrations' satisfying certain axioms relating them. These abstract ...

structure on the category of simplicial sets are known as

Kan fibration In mathematics, Kan complexes and Kan fibrations are part of the theory of simplicial sets. Kan fibrations are the fibrations of the standard model category structure on simplicial sets and are therefore of fundamental importance. Kan complexes are ...

s, and the fibrant objects are known as

Kan complex In mathematics, Kan complexes and Kan fibrations are part of the theory of simplicial sets. Kan fibrations are the fibrations of the standard model category structure on simplicial sets and are therefore of fundamental importance. Kan complexes are ...

es. Some of Kan's later work concerned model categories and other homotopical categories. Especially noteworthy are his work with Aldridge Bousfield on completions and homotopy limits, and his work with William Dwyer on simplicial localizations of relative categories.

References

External links

*
Kan memorial note at the MIT Mathematics Department
{{DEFAULTSORT:Kan, Daniel 20th-century Dutch mathematicians Israeli expatriates in the United States 20th-century Israeli mathematicians Hebrew University of Jerusalem alumni Massachusetts Institute of Technology faculty Topologists 1927 births 2013 deaths Dutch emigrants to Israel

Career

Work

See also

References

External links