# postulate

101

**Saccheri quadrilateral**— A Saccheri quadrilateral is a quadrilateral with two equal sides perpendicular to the base. It is named after Giovanni Gerolamo Saccheri, who used it extensively in his book Euclid vindicatus (1733), an attempt to prove the parallel postulate.… …102

**Ibn al-Haytham**— Infobox Muslim scholars | notability = Muslim scientist| era = Islamic Golden Age| color = #cef2e0 | | image caption = Ibn al Haytham drawing taken from a 1982 Iraqi 10 dinar note. | | name = Unicode|Abū ‘Alī al Ḥasan ibn al Ḥasan ibn al Haytham… …103

**Statistical mechanics**— is the application of probability theory, which includes mathematical tools for dealing with large populations, to the field of mechanics, which is concerned with the motion of particles or objects when subjected to a force.Statistical mechanics …104

**Absolute geometry**— is a geometry based on an axiom system for Euclidean geometry that does not assume the parallel postulate or any of its alternatives. The term was introduced by János Bolyai in 1832.[1] It is sometimes referred to as neutral geometry,[2] as it is …105

**Heinrich Hermann Robert Koch**— Robert Koch Kochs Unterschrift Heinrich Hermann Robert Koch (* 11. Dezember 1843 in Clausthal; † 27. Mai 1910 …106

**cosmos**— /koz meuhs, mohs/, n., pl. cosmos, cosmoses for 2, 4. 1. the world or universe regarded as an orderly, harmonious system. 2. a complete, orderly, harmonious system. 3. order; harmony. 4. any composite plant of the genus Cosmos, of tropical… …107

**non-Euclidean geometry**— geometry based upon one or more postulates that differ from those of Euclid, esp. from the postulate that only one line may be drawn through a given point parallel to a given line. [1870 75; NON + EUCLIDEAN] * * * Any theory of the nature of… …108

**Riemannian geometry**— Geom. 1. Also called elliptic geometry. the branch of non Euclidean geometry that replaces the parallel postulate of Euclidean geometry with the postulate that in a plane every pair of distinct lines intersects. Cf. hyperbolic geometry. 2. the… …109

**Alhazen**— For the Moon crater, see Alhazen (crater). For the asteroid, see 59239 Alhazen. Alhazen Alhazen (Ibn al Haytham) …110

**Sidgwick, Henry**— Sidgwick C.A.J.Coady Unlike John Stuart Mill or Jeremy Bentham, Henry Sidgwick’s is hardly a household name in intellectual circles beyond the world of professional philosophy. His standing amongst many contemporary moral philosophers as possibly …