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Hendrik Willem Lenstra Jr. (born 16 April 1949,
Zaandam Zaandam () is a city in the province of North Holland, Netherlands. It is the main city of the municipality of Zaanstad, and received city rights in 1811. It is located on the river Zaan, just north of Amsterdam. The statistical district Zaand ...
) is 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 ...
.


Biography

Lenstra received his
doctorate A doctorate (from Latin ''docere'', "to teach"), doctor's degree (from Latin ''doctor'', "teacher"), or doctoral degree is an academic degree awarded by universities and some other educational institutions, derived from the ancient formalism ''li ...
from the
University of Amsterdam The University of Amsterdam (abbreviated as UvA, nl, Universiteit van Amsterdam) is a public research university located in Amsterdam, Netherlands. The UvA is one of two large, publicly funded research universities in the city, the other being ...
in 1977 and became a professor there in 1978. In 1987 he was appointed to the faculty of the
University of California, Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant u ...
; starting in 1998, he divided his time between Berkeley and the
University of Leiden Leiden University (abbreviated as ''LEI''; nl, Universiteit Leiden) is a public research university in Leiden, Netherlands. The university was founded as a Protestant university in 1575 by William, Prince of Orange, as a reward to the city of Le ...
, until 2003, when he retired from Berkeley to take a full-time position at Leiden. Three of his brothers,
Arjen Lenstra Arjen Klaas Lenstra (born 2 March 1956, in Groningen) is a Dutch mathematician, cryptographer and computational number theorist. He is currently a professor at the École Polytechnique Fédérale de Lausanne (EPFL) where he heads of the Laborator ...
, Andries Lenstra, and Jan Karel Lenstra, are also mathematicians. Jan Karel Lenstra is the former director of the
Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...
Centrum Wiskunde & Informatica The (abbr. CWI; English: "National Research Institute for Mathematics and Computer Science") is a research centre in the field of mathematics and theoretical computer science. It is part of the institutes organization of the Dutch Research Co ...
(CWI). Hendrik Lenstra was the Chairman of the Program Committee of the International Congress of Mathematicians in 2010.


Scientific contributions

Lenstra has worked principally in
computational number theory In mathematics and computer science, computational number theory, also known as algorithmic number theory, is the study of computational methods for investigating and solving problems in number theory and arithmetic geometry, including algorithm ...
. He is well known for: * Co-discovering of the
Lenstra–Lenstra–Lovász lattice basis reduction algorithm The Lenstra–Lenstra–Lovász (LLL) lattice basis reduction algorithm is a polynomial time lattice reduction algorithm invented by Arjen Lenstra, Hendrik Lenstra and László Lovász in 1982. Given a basis \mathbf = \ with ''n''-dimensional int ...
(in 1982); * Developing an polynomial-time algorithm for solving a feasibility
Integer programming An integer programming problem is a mathematical optimization or feasibility program in which some or all of the variables are restricted to be integers. In many settings the term refers to integer linear programming (ILP), in which the objective ...
problem when the number of variables is fixed (in 1983); * Discovering the elliptic curve factorization method (in 1987); * Computing all solutions to the inverse Fermat equation (in 1992); * The Cohen–Lenstra heuristics - a set of precise conjectures about the structure of
class group In number theory, the ideal class group (or class group) of an algebraic number field is the quotient group where is the group of fractional ideals of the ring of integers of , and is its subgroup of principal ideals. The class group is a mea ...
s of
quadratic field In algebraic number theory, a quadratic field is an algebraic number field of degree two over \mathbf, the rational numbers. Every such quadratic field is some \mathbf(\sqrt) where d is a (uniquely defined) square-free integer different from 0 a ...
s.


Awards and honors

In 1984 Lenstra became member of the Royal Netherlands Academy of Arts and Sciences. He won the
Fulkerson Prize The Fulkerson Prize for outstanding papers in the area of discrete mathematics is sponsored jointly by the Mathematical Optimization Society (MOS) and the American Mathematical Society (AMS). Up to three awards of $1,500 each are presented at e ...
in 1985 for his research using the
geometry of numbers Geometry of numbers is the part of number theory which uses geometry for the study of algebraic numbers. Typically, a ring of algebraic integers is viewed as a lattice in \mathbb R^n, and the study of these lattices provides fundamental informatio ...
to solve integer programs with few variables in time polynomial in the number of constraints. He was awarded the
Spinoza Prize The Spinoza Prize ( nl, Spinozapremie) is an annual award of 2.5 million euro, to be spent on new research given by the Dutch Research Council (NWO). The award is the highest scientific award in the Netherlands. It is named after the philosopher ...
in 1998, and on 24 April 2009 he was made a Knight of the
Order of the Netherlands Lion The Order of the Netherlands Lion, also known as the Order of the Lion of the Netherlands ( nl, De Orde van de Nederlandse Leeuw, french: L'Ordre du Lion Néerlandais) is a Dutch order of chivalry founded by King William I of the Netherlands on ...
. In 2009, he was awarded a Gauss Lecture by the
German Mathematical Society The German Mathematical Society (german: Deutsche Mathematiker-Vereinigung, DMV) is the main professional society of German mathematicians and represents German mathematics within the European Mathematical Society (EMS) and the International Math ...
. In 2012 he became a fellow of the
American Mathematical Society The American Mathematical Society (AMS) is an association of professional mathematicians dedicated to the interests of mathematical research and scholarship, and serves the national and international community through its publications, meetings, ...
.List of Fellows of the American Mathematical Society
retrieved 2013-01-27.


Publications

* ''Euclidean Number Fields.'' Parts 1-3, Mathematical Intelligencer 1980 * with A. K. Lenstra: ''Algorithms in Number Theory.'' pp. 673–716, In Jan van Leeuwen (ed.): ''Handbook of Theoretical Computer Science, Vol. A: Algorithms and Complexity.'' Elsevier and MIT Press 1990, , .

Bulletin of the AMS, vol. 26, 1992, pp. 211–244.
''Primality testing algorithms.''
Séminaire Bourbaki 1981. * with Stevenhagen
''Artin reciprocity and Mersenne Primes.''
Nieuw Archief for Wiskunde 2000. * with Stevenhagen: '' Chebotarev and his density theorem.'' Mathematical Intelligencer 1992 (Online at Lenstra's Homepage).
''Profinite Fibonacci Numbers'', December 2005, PDF


See also

* Print Gallery (M. C. Escher)


References

*


External links

* * , Homepage at the Leiden Mathematisch Instituut * {{DEFAULTSORT:Lenstra, Hendrik 1949 births Living people 20th-century Dutch mathematicians 21st-century Dutch mathematicians Members of the Royal Netherlands Academy of Arts and Sciences Number theorists Spinoza Prize winners University of Amsterdam alumni University of Amsterdam faculty Leiden University faculty University of California, Berkeley College of Letters and Science faculty Fellows of the American Mathematical Society Dutch expatriates in the United States People from Zaanstad