Samuel Roberts FRS (15 December 1827, in

Horncastle, Lincolnshire Horncastle is a town and civil parish in the East Lindsey district in Lincolnshire, east of Lincoln, England, Lincoln. Its population was 6,815 at the 2011 census and estimated at 7,123 in 2019. A section of the ancient Roman Britain, Roman wa ...

– 18 September 1913, in

London London is the capital and largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary down to the North Sea, and has been a majo ...

) was a British mathematician. Roberts studied at

Queen Elizabeth's Grammar School, Horncastle Queen Elizabeth's Grammar School, Horncastle, is a co-educational grammar school with academy status in Horncastle, Lincolnshire, England. In 2009, there were 877 pupils, of whom 271 were in the sixth form. Although royally chartered by Que ...

. He matriculated in 1845 at the

University of London The University of London (UoL; abbreviated as Lond or more rarely Londin in post-nominals) is a federal public research university located in London, England, United Kingdom. The university was established by royal charter in 1836 as a degree ...

, where he earned in 1847 his bachelor's degree in mathematics and in 1849 his master's degree in mathematics and physics, as first in his class. Next he studied law and became a solicitor in 1853. After a few years of law practice he abandoned his law career and returned to mathematics, although he never had an academic position. He had his first mathematical paper published in 1848. In 1865 he was an important participant in the founding of the

London Mathematical Society The London Mathematical Society (LMS) is one of the United Kingdom's learned societies for mathematics (the others being the Royal Statistical Society (RSS), the Institute of Mathematics and its Applications (IMA), the Edinburgh Mathematical S ...

(LMS). From 1866 to 1892 he acted as legal counsel for LMS, from 1872 to 1880 he was the organization's treasurer, and from 1880 to 1882 its president. In 1896 he received the De Morgan Medal of the LMS. In 1878 he was elected FRS. Roberts published papers in several fields of mathematics, including

geometry Geometry (; ) is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space such as the distance, shape, size, and relative position of figures. A mathematician who works in the field of geometry is c ...

interpolation In the mathematical field of numerical analysis, interpolation is a type of estimation, a method of constructing (finding) new data points based on the range of a discrete set of known data points. In engineering and science, one often has a n ...

theory, and

Diophantine equation In mathematics, a Diophantine equation is an equation, typically a polynomial equation in two or more unknowns with integer coefficients, such that the only solutions of interest are the integer ones. A linear Diophantine equation equates to a c ...

s. Roberts and Pafnuty Chebyschev are jointly credited with the Roberts-Chebyshev theorem related to four-bar linkages.

Roberts's triangle theorem Roberts's triangle theorem, a result in discrete geometry, states that every simple arrangement of lines, arrangement of n lines has at least n-2 triangular faces. Thus, three lines form a triangle, four lines form at least two triangles, five l ...

, on the minimum number of triangles that

n

lines can form, is also named after Roberts, who published the theorem (with an unconvincing proof) in 1889.

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* {{DEFAULTSORT:Roberts, Samuel 19th-century English mathematicians 20th-century English mathematicians 1827 births 1913 deaths Fellows of the Royal Society People from Horncastle, Lincolnshire Alumni of the University of London People educated at Queen Elizabeth's Grammar School, Horncastle