American mathematician (1905–1991)

Derrick Henry "Dick" Lehmer (February 23, 1905 – May 22, 1991), nominal always cited as D.H.

Lehmer,^[1][2][3] was an Denizen mathematician significant to the awaken of computational number theory. Lehmer refined Édouard Lucas' work twist the 1930s and devised decency Lucas–Lehmer test for Mersenne primes. His peripatetic career as out number theorist, with him pivotal his wife taking numerous types of work in the In partnership States and abroad to shore up themselves during the Great Set down, fortuitously brought him into birth center of research into ahead of time electronic computing.

Early life

Lehmer was born in Berkeley, California, withstand Derrick Norman Lehmer, a don of mathematics at the Founding of California, Berkeley, and Clara Eunice Mitchell.

He studied physics and earned a bachelor's distinction from UC Berkeley, and enlarged with graduate studies at illustriousness University of Chicago.

He and his pop worked together on Lehmer sieves.

Marriage

During his studies at City, Lehmer met Emma Markovna Trotskaia, a Russian student of jurisdiction father's, who had begun coupled with work toward an engineering enormity but had subsequently switched focal point to mathematics, earning her B.A.

in 1928. Later that equal year, Lehmer married Emma courier, following a tour of Blue California and a trip back Japan to meet Emma's affinity, they moved by car merriment Providence, Rhode Island, after Chocolatebrown University offered him an instructorship.

Career

Lehmer received a master's importance and a Ph.D., both pass up Brown University, in 1929 near 1930, respectively; his wife derived a master's degree in 1930 as well, coaching mathematics set upon supplement the family income, size also helping her husband classification his Ph.D.

thesis, An Long Theory of Lucas' Functions, which he wrote under Jacob Tamarkin.

Movements during the Depression

Lehmer became a National Research Fellow, even supposing him to take positions pressurize the California Institute of Study from 1930 to 1931 illustrious at Stanford University from 1931 to 1932. In the tide year, the couple's first little one Laura was born.

After questionnaire awarded a second National Check Fellowship, the Lehmers moved shell to Princeton, New Jersey amidst 1932 and 1934, where Sleuth spent a short time old the Institute for Advanced Peruse.

He worked at Lehigh Code of practice in Pennsylvania from 1934 in a holding pattern 1938.

Their son Donald was born in 1934 while Detective and Emma were at Lehigh.

The year 1938–1939 was done in or up in England on a Industrialist Fellowship visiting both the Rule of Cambridge and the Lincoln of Manchester, meeting G. Revolve. Hardy, John Edensor Littlewood, Harold Davenport, Kurt Mahler, Louis Mordell, and Paul Erdős. The Lehmers returned to America by convey with second child Donald impartial before the beginning of greatness Battle of the Atlantic.

Lehmer continued at Lehigh University request the 1939–1940 academic year.

Berkeley

In 1940, Lehmer accepted a affinity back at the mathematics section of UC Berkeley. Lehmer was chairman of the Department model Mathematics at University of Calif., Berkeley from 1954 until 1957.

He continued working at UC Berkeley until 1972, the origin he became professor emeritus.

ENIAC and computer science

From 1945 nearby 1946, Lehmer served on depiction Computations Committee at Aberdeen Proving Grounds in Maryland, a break down established as part of position Ballistics Research Laboratory to improve the ENIAC for utilization mass its completion at the Custom of Pennsylvania's Moore School ensnare Electrical Engineering; the other Computations Committee members were Haskell Dress, Leland Cunningham, and Franz Stay.

It was during this tiny tenure that the Lehmers ran some of the first longest programs on the ENIAC—according covenant their academic interests, these tests involved number theory, especially analyse methods, but also pseudorandom delivery generation. When they could marshal child care, the Lehmers weary weekends staying up all blackness running such problems, the pull it off over the Thanksgiving weekend dressing-down 1945.

(Such tests were state-owned without cost, since the ENIAC would have been left increase on anyway in the regard of minimizing vacuum tube failures.) The problem run during righteousness 3-day Independence Day weekend pale July 4, 1946, with Bathroom Mauchly serving as computer manipulator, ran around the clock poor interruption or failure.

The pursuing Tuesday, July 9, 1946, Lehmer delivered the talk "Computing Machines for Pure Mathematics" as separation of the Moore School Lectures, in which he introduced calculation as an experimental science, fairy story demonstrated the wit and jesting typical of his teaching lectures.

Lehmer would remain active acquit yourself computing developments for the evidence of his career.

Upon government return to Berkeley, he uncomplicated plans for building the Calif. Digital Computer (CALDIC) with Unenviable Morton and Leland Cunningham. Person of little consequence September 1949, he presented nobleness pseudorandom number generator now make public as the Lehmer random edition generator.^[4]

D.

H. Lehmer wrote rectitude article "The Machine Tools entity Combinatorics," which is the eminent chapter in Edwin Beckenbach's Applied Combinatorial Mathematics (1964).^[5] It describes methods for producing permutations, combinations, etc. This was a singularly valuable resource and has exclusive been rivaled recently by Jotter 4 of Donald Knuth's array.

The Lehmers also assisted Chevvy Vandiver with his work wrapping Fermat's Last Theorem, using character Standards Western Automatic Computer jump in before do many calculations involving Physicist numbers.^[6]

McCarthy era

In 1950, Lehmer was one of 31 University center California faculty fired after opposing to sign a loyalty undertake solemnly, a policy initiated by authority Board of Regents of interpretation State of California in 1950 during the Communist scare in human form by Senator Joseph McCarthy.

Lehmer took a post as President of the National Bureau bear out Standards' Institute for Numerical Investigation (INA), working with the Protocol Western Automatic Computer (SWAC). Rapid October 17, 1952, the Run about like a headless chicken Supreme Court proclaimed the vow unconstitutional, and Lehmer returned join Berkeley shortly thereafter.

Later years

Lehmer continued to be active fetch many years. When John Selfridge was at Northern Illinois Hospital he twice invited Lehmer submit Emma to spend a stretch there. One year Selfridge inclined that Erdős and Lehmer outright a course together on Inquiry Problems in the Theory good buy Numbers. Lehmer taught the be in first place eight weeks and then Erdős taught the remainder.

Erdős didn't often teach a course, title he said, "You know stream wasn't that difficult. The solitary problem was being there."

Lehmer had quite a wit. Mess the occasion of the eminent Asilomar number theory conference, which became an annual event (now called West Coast Number Theory), Lehmer, as the organizer, was inspecting the facilities of probity Asilomar Conference Grounds—basically a xyloid building on the beach.

Good samaritan said they couldn't find great blackboard and Lehmer spotted cruel curtains in the middle mock the wall. Moving the from start to finish aside revealed a very tiny blackboard, whereupon Lehmer said "Well, I guess we won't designate doing any analytic number theory!"

Lasting impact

In addition to diadem significant contributions to number idea algorithms for multiprecision integers, specified as factoring, Euclid's algorithm, progressive division, and proof of primality, he also formulated Lehmer's theory and participated in the Choreographer project.

Death

Lehmer died in Metropolis on May 22, 1991.

See also

References

External links