PQ
- Pascal's triangle: named after and discovered by Pascal, but identified several times before him independently.
- Pell's equation, studied in ancient India, but mistakenly attributed to John Pell by Leonhard Euler. Apparently Euler confused Lord Brouncker (first European mathematician to find a general solution of the equation) with Pell.
- Penrose triangle, an impossible object, first created by the Swedish artist Oscar Reutersvärd in 1934. The mathematician Roger Penrose independently devised and popularised it in the 1950s
- Playfair cipher, invented by Charles Wheatstone in 1854, but named after Lord Playfair who promoted its use.
- Poisson spot: predicted by Fresnel's theory of diffraction, named after Poisson, who ridiculed the theory, especially its prediction of the existence of this spot
- Prim's algorithm: the algorithm was developed in 1930, 27 years before Prim independently did, by the Czech mathematician Vojtěch Jarník.
- Prinzmetal angina: also known as variant angina, referring to angina (chest pain) caused by vasospasm of the coronary arteries. Described twice in the 1930s before being published by Prinzmetal in 1959.
- Pythagorean theorem, named after the mathematician Pythagoras, although it was known before him to Babylonian mathematicians (although it is not known if the Babylonians possessed a proof of the result; yet it is not known either, whether Pythagoras proved the result).
Read more about this topic: List Of Examples Of Stigler's Law