Aleksey Vasilievich Letnikov , (1837-1888) was a Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

n mathematician.

Aleksey graduated from the Constantin Institute for Border-lines in Moscow

Moscow

Moscow is the capital, the most populous city, and the most populous federal subject of Russia. The city is a major political, economic, cultural, scientific, religious, financial, educational, and transportation centre of Russia and the continent...

. After graduation he attended classes at the Moscow University

Moscow State University

Lomonosov Moscow State University , previously known as Lomonosov University or MSU , is the largest university in Russia. Founded in 1755, it also claims to be one of the oldest university in Russia and to have the tallest educational building in the world. Its current rector is Viktor Sadovnichiy...

 and Sorbonne

Sorbonne

The Sorbonne is an edifice of the Latin Quarter, in Paris, France, which has been the historical house of the former University of Paris...

. In 1860 he became an Instructor of Mathematics at the Constantin Institute. He obtained degrees of Master

Master's degree

A master's is an academic degree granted to individuals who have undergone study demonstrating a mastery or high-order overview of a specific field of study or area of professional practice...

 (1868) and Ph.D.

Ph.D.

A Ph.D. is a Doctor of Philosophy, an academic degree.Ph.D. may also refer to:* Ph.D. , a 1980s British group*Piled Higher and Deeper, a web comic strip*PhD: Phantasy Degree, a Korean comic series* PhD Docbook renderer, an XML renderer...

 (1874) from the Moscow University.
In 1868 he became a Professor of the Imperial Moscow Technical School, in 1879-1880 he was an Inspector

Inspector

Inspector is both a police rank and an administrative position, both used in a number of contexts. However, it is not an equivalent rank in each police force.- Australia :...

 of the School. From 1883 he was the principal of the Alexander Commercial School ; from 1884 he was a Corresponding Member of Russian Academy of Sciences

Russian Academy of Sciences

The Russian Academy of Sciences consists of the national academy of Russia and a network of scientific research institutes from across the Russian Federation as well as auxiliary scientific and social units like libraries, publishers and hospitals....

. Letnikov died in 1888 in Moscow and buried in Alexandroskoe cemetery http://www.pravoslavie.ru/jurnal/050926122018.

Letnikov's most renown contribution is the creation of the Grunwald-Letnikov differintegral

Grunwald-Letnikov differintegral

In mathematics, the Grünwald–Letnikov derivative is a basic extension of the derivative in fractional calculus, that allows one to take the derivative a non-integer number of times...

. He also published results about Analytic geometry

Analytic geometry

Analytic geometry, or analytical geometry has two different meanings in mathematics. The modern and advanced meaning refers to the geometry of analytic varieties...

, Spherical function

Spherical function

Spherical function can refer to* Spherical harmonics*Zonal spherical function...

s, Ordinary differential equation

Ordinary differential equation

In mathematics, an ordinary differential equation is a relation that contains functions of only one independent variable, and one or more of their derivatives with respect to that variable....

 and Non-Euclidean geometry

Non-Euclidean geometry

Non-Euclidean geometry is the term used to refer to two specific geometries which are, loosely speaking, obtained by negating the Euclidean parallel postulate, namely hyperbolic and elliptic geometry. This is one term which, for historical reasons, has a meaning in mathematics which is much...

.