form of closure product
111photoreception — photoreceptive, adj. /foh toh ri sep sheuhn/, n. the physiological perception of light. [1905 10; PHOTO + RECEPTION] * * * Biological responses to stimulation by light, most often referring to the mechanism of vision. In one celled organisms such …
112Axiom of choice — This article is about the mathematical concept. For the band named after it, see Axiom of Choice (band). In mathematics, the axiom of choice, or AC, is an axiom of set theory stating that for every family of nonempty sets there exists a family of …
113Projective transformation — A projective transformation is a transformation used in projective geometry: it is the composition of a pair of perspective projections. It describes what happens to the perceived positions of observed objects when the point of view of the… …
114Barack Obama — Barack and Obama redirect here. For other uses, see Barak (disambiguation) and Obama (disambiguation). For the Kenyan economist, President Obama s father, see Barack Obama, Sr …
115Afghanistan — /af gan euh stan /, n. a republic in central Asia, NW of India and E of Iran. 23,738,085; 250,000 sq. mi. (647,500 sq. km). Cap.: Kabul. * * * Afghanistan Introduction Afghanistan Background: Afghanistan s recent history is characterized by war… …
116Continuous function — Topics in Calculus Fundamental theorem Limits of functions Continuity Mean value theorem Differential calculus  Derivative Change of variables Implicit differentiation Taylor s theorem Related rates …
117Naive set theory — This article is about the mathematical topic. For the book of the same name, see Naive Set Theory (book). Naive set theory is one of several theories of sets used in the discussion of the foundations of mathematics.[1] The informal content of… …
1182-satisfiability — In computer science, 2 satisfiability (abbreviated as 2 SAT or just 2SAT) is the problem of determining whether a collection of two valued (Boolean or binary) variables with constraints on pairs of variables can be assigned values satisfying all… …
119Cryptanalysis of the Enigma — enabled the western Allies in World War II to read substantial amounts of secret Morse coded radio communications of the Axis powers that had been enciphered using Enigma machines. This yielded military intelligence which, along with that from… …
120Migraines associated with PFO heart defect — PFO, or patent foramen ovale, is a heart valve in humans that usually closes off at or shortly after birth. The valve’s function is to let the circulating blood bypass the lungs, which the body doesn t rely on until a newborn starts breathing air …
