**Simon Lhuilier** was a Swiss mathematician who worked on analysis, topology and probability.

- There was a strange episode in Lhuilier's life when he was still young.
- A wealthy relation proposed that he would leave Lhuilier a large fortune if he followed a career in the church.
- However, Lhuilier had already found the attraction of mathematics and money was not going to make him give up the attractions of the topic so he refused his relative's offer.
- Lhuilier was an exceptional secondary school pupil and he went on to study mathematics at a Calvin Academy where he was taught mathematics by one of Euler's former pupils, Louis Bertrand, and physics by Georges-Louis Le Sage.
- The next career move by Lhuilier was also as a result of him knowing Le Sage.
- Le Sage tried to persuade Lhuilier to submit an entry to write a physics text but Lhuilier preferred to enter the competition to write a mathematics text.
- Lhuilier's proposal won the competition giving him the right to write a mathematics textbook to be used in Polish schools.
- Lhuilier spent eleven years at Pulawy.
- Adam Jerzy Czartoryski proved an extremely bright and gifted pupil and, in addition to his tutoring duties, Lhuilier found time to write his mathematics text, undertake research in mathematics which resulted in several fine publications, and enjoy a busy social life with hunting parties.
- Lhuilier submitted the paper Exposition élémentaire des principes des calculs supérieurs Ⓣ(Elementary exposition of the principles of superior calculus) and his essay won the prize and was published in Berlin in 1786.
- The standard concepts and notation for derivatives, and the standard elementary theorems on limits which appear in an undergraduate calculus text today appear in a remarkably similar form in Lhuilier's prize winning essay.
- Lhuilier introduced the notation "lim", and was the first to allow two-sided limits.
- The topic of limits was a particularly fortunate one for Lhuilier since he had been thinking about limits before the topic was ever proposed for the prize.
- Pfleiderer, who had become a friend through the Polish episode, was by this time teaching mathematics in Tübingen and Lhuilier went to be with Pfleiderer there.
- In the following year Lhuilier was offered a chair of mathematics in Leiden, but he preferred to compete for the chair in Geneva which had been held by his former teacher Louis Bertrand.
- Having won the competition, Lhuilier was appointed in 1795 and held this chair until he retired in 1823.
- Not only was 1795 the year of his appointment to the Academy in Geneva but it was a year marked by two other important events in Lhuilier's life.
- Lhuilier also corrected Euler's solution of the Königsberg bridge problem.
- One further work by Lhuilier is worth commenting on.
- His most famous pupil was Charles-François Sturm who studied under Lhuilier during the last few years of his career in Geneva.

Born 24 April 1750, Geneva, Switzerland. Died 28 March 1840, Geneva, Switzerland.

View full biography at MacTutor

Ancient Indian, Origin Switzerland, Topology

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive