Dame Mary Lucy Cartwright, (17 December 1900 – 3 April 1998) was a British mathematician. She was one of the pioneers of what would later become known as chaos theory. Along with J. E. Littlewood, Cartwright saw many solutions to a problem which would later be seen as an example of the butterfly effect. Early life and education Mary Cartwright was born on 17 December 1900, in Aynho, Northamptonshire, where her father William Digby was vicar. Through her grandmother Jane Holbech, she descended from poet John Donne and William Mompesson, Vicar of Eyam. She had four siblings, two older and two younger: John (born 1896), Nigel (born 1898), Jane (born 1905), and William (born 1907). Her early education was at Leamington High School (1912–1915), and then at Gravely Manor School in Boscombe (1915–1916) before completion in Godolphin School in Salisbury (1916–1919). Cartwright studied mathematics at St Hugh's College, Oxford, graduating in 1923 with a first class degree. She was the first woman to attain the final degree lectures and to obtain a first. She briefly taught at Alice Ottley School in Worcester and Wycombe Abbey School in Buckinghamshire before returning to Oxford in 1928 to read for her D.Phil. Cartwright was supervised by G. H. Hardy in her doctoral studies. During the academic year 1928–9 Hardy was at Princeton, so it was E. C. Titchmarsh who took over the duties as a supervisor. Her thesis "The Zeros of Integral Functions of Special Types" was examined by J. E. Littlewood, whom she met for the first time as an external examiner in her oral examination for that 1930 D.Phil. In 1930, Cartwright was awarded a Yarrow Research Fellowship and went to Girton College, Cambridge to continue working on the topic of her doctoral thesis. Attending Littlewood's lectures, she solved one of the open problems which he posed. Her mathematical theorem, now known as Cartwright's Theorem, gives an estimate for the maximum modulus of an analytic function that takes the same value no more than p times in the unit disc. To prove the theorem she used a new approach, applying a technique introduced by Lars Ahlfors for conformal mappings. Career Throughout her career, Cartwright wrote over ninety articles on several different mathematical concepts. Her contributions extended to topics such as the Dirichlet series, Abel summation, directions of Borel spreads, analytic functions regular on the unit disk, the zeros of integral functions,