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17-letter words containing c, u, l, t, r, a

  • national security — defence of a country
  • natural deduction — (logic)   A set of rules expressing how valid proofs may be constructed in predicate logic. In the traditional notation, a horizontal line separates premises (above) from conclusions (below). Vertical ellipsis (dots) stand for a series of applications of the rules. "T" is the constant "true" and "F" is the constant "false" (sometimes written with a LaTeX \perp). "^" is the AND (conjunction) operator, "v" is the inclusive OR (disjunction) operator and "/" is NOT (negation or complement, normally written with a LaTeX \neg). P, Q, P1, P2, etc. stand for propositions such as "Socrates was a man". P[x] is a proposition possibly containing instances of the variable x, e.g. "x can fly". A proof (a sequence of applications of the rules) may be enclosed in a box. A boxed proof produces conclusions that are only valid given the assumptions made inside the box, however, the proof demonstrates certain relationships which are valid outside the box. For example, the box below labelled "Implication introduction" starts by assuming P, which need not be a true proposition so long as it can be used to derive Q. Truth introduction: - T (Truth is free). Binary AND introduction: ----------- | . | . | | . | . | | Q1 | Q2 | ----------- Q1 ^ Q2 (If we can derive both Q1 and Q2 then Q1^Q2 is true). N-ary AND introduction: ---------------- | . | .. | . | | . | .. | . | | Q1 | .. | Qn | ---------------- Q1^..^Qi^..^Qn Other n-ary rules follow the binary versions similarly. Quantified AND introduction: --------- | x . | | . | | Q[x] | --------- For all x . Q[x] (If we can prove Q for arbitrary x then Q is true for all x). Falsity elimination: F - Q (Falsity opens the floodgates). OR elimination: P1 v P2 ----------- | P1 | P2 | | . | . | | . | . | | Q | Q | ----------- Q (Given P1 v P2, if Q follows from both then Q is true). Exists elimination: Exists x . P[x] ----------- | x P[x] | | . | | . | | Q | ----------- Q (If Q follows from P[x] for arbitrary x and such an x exists then Q is true). OR introduction 1: P1 ------- P1 v P2 (If P1 is true then P1 OR anything is true). OR introduction 2: P2 ------- P1 v P2 (If P2 is true then anything OR P2 is true). Similar symmetries apply to ^ rules. Exists introduction: P[a] ------------- Exists x.P[x] (If P is true for "a" then it is true for all x). AND elimination 1: P1 ^ P2 ------- P1 (If P1 and P2 are true then P1 is true). For all elimination: For all x . P[x] ---------------- P[a] (If P is true for all x then it is true for "a"). For all implication introduction: ----------- | x P[x] | | . | | . | | Q[x] | ----------- For all x . P[x] -> Q[x] (If Q follows from P for arbitrary x then Q follows from P for all x). Implication introduction: ----- | P | | . | | . | | Q | ----- P -> Q (If Q follows from P then P implies Q). NOT introduction: ----- | P | | . | | . | | F | ----- / P (If falsity follows from P then P is false). NOT-NOT: //P --- P (If it is not the case that P is not true then P is true). For all implies exists: P[a] For all x . P[x] -> Q[x] ------------------------------- Q[a] (If P is true for given "a" and P implies Q for all x then Q is true for a). Implication elimination, modus ponens: P P -> Q ---------- Q (If P and P implies Q then Q). NOT elimination, contradiction: P /P ------ F (If P is true and P is not true then false is true).
  • natural frequency — the frequency at which a system vibrates when set in free vibration
  • natural harmonics — harmonics of a note produced on a stringed instrument by lightly touching an open or unstopped sounded string.
  • natural hat trick — three goals scored in succession by one player in one game or one period.
  • natural resources — a naturally occurring source of wealth, as land or water.
  • natural selection — the process by which forms of life having traits that better enable them to adapt to specific environmental pressures, as predators, changes in climate, or competition for food or mates, will tend to survive and reproduce in greater numbers than others of their kind, thus ensuring the perpetuation of those favorable traits in succeeding generations.
  • natural-resources — a naturally occurring source of wealth, as land or water.
  • neuropathological — (medicine) Of, pertaining to, or arising from neuropathology, the pathology of nerve tissue.
  • non-instructional — the act or practice of instructing or teaching; education.
  • nuclear chemistry — the branch of chemistry concerned with nuclear reactions
  • nuclear deterrent — a country's nuclear weapons viewed as a deterrent to other countries from attacking
  • nuclear radiation — Physics. radiation in the form of elementary particles emitted by an atomic nucleus, as alpha rays or gamma rays, produced by decay of radioactive substances or by nuclear fission.
  • nuclear scientist — a scientist who studies nuclear physics
  • nuclear threshold — the point in war at which a combatant brings nuclear weapons into use
  • numerical control — control of a machine tool, or other device used in a manufacturing process, by a computer, other control circuitry, or recorded digital commands.
  • opportunistically — adhering to a policy of opportunism; practicing opportunism.
  • osculating circle — circle of curvature.
  • palace revolution — a challenge to or overthrow of a sovereign or other leader by members of the ruling family or group.
  • parallel computer — parallel processor
  • particularization — to make particular.
  • peacock butterfly — a European nymphalid butterfly, Inachis io, having reddish-brown wings each marked with a purple eyespot
  • perpetual spinach — a variety of spinach that keeps producing edible leaves
  • personal computer — a compact computer that uses a microprocessor and is designed for individual use, as by a person in an office or at home or school, for such applications as word processing, data management, financial analysis, or computer games. Abbreviation: PC.
  • plastics industry — the industry that makes plastics
  • pocket calculator — an electronic calculator small enough to be carried on one's person.
  • political refugee — a person who has fled from a homeland because of political persecution.
  • portable computer — (computer)   (Commonly, "laptop") A portable personal computer you can carry with one hand. Some laptops run so hot that it would be quite uncomforable to actually use them on your lap for long. The term "notebook" is often used to describe these, though it also implies a low weight (less than 2kg). A "luggable" is one you could carry in one hand but is so heavy you wouldn't want to. One that can by easily operated while held in one hand is a "palmtop". The computer considered by most historians to be the first true portable computer was the Osborne 1 but see the link below for other contenders.
  • postbaccalaureate — bachelor's degree.
  • poststructuralism — a variation of structuralism, often seen as a critique, emphasizing plurality of meaning and instability of concepts that structuralism uses to define society, language, etc.
  • pre-qualification — a quality, accomplishment, etc., that fits a person for some function, office, or the like.
  • probability curve — a curve that describes the distribution of probability over the values of a random variable.
  • procurator fiscal — In the Scottish legal system, the procurator fiscal is a public official who puts people on trial.
  • product liability — the responsibility of a manufacturer for injury or loss caused by its product.
  • product placement — Product placement is a form of advertising in which a company has its product placed where it can be clearly seen during a film or television programme.
  • production values — the quality of a media production (such as a film) in regards to elements such as colours, quality, style, etc
  • prostatic utricle — a small pouch near the prostate gland that opens into the urethra.
  • pseudo-historical — of, pertaining to, treating, or characteristic of history or past events: historical records; historical research.
  • pseudo-moralistic — a person who teaches or inculcates morality.
  • quadratic formula — the formula for determining theroots of a quadratic equation from its coefficients: .
  • quality assurance — a system for ensuring a desired level of quality in the development, production, or delivery of products and services: Quality assurance for nursing homes begins with a set of standards. Abbreviation: QA.
  • quality paperback — a softbound book that is usually larger and more expensive than a mass market paperback and is sold primarily in bookstores as a trade book.
  • quantum cell wire — (electronics, computing)   (Or "quantum wire", "binary wire") Quantum cells arranged in a line to carry signals. Adjacent cells with the same orientation are at a low energy state and a change of orientation at one end of a quantum wire propagates along the wire, transmitting a signal. However, unlike conventional wire, since only the orientation of charge pairs changes, no current flows. Circuits created using quantum cell wires are referred to as Quantum-dot Wireless Digital Circuits, see quantum dot, Quantum-dot Cellular Automata.
  • quattuordecillion — a cardinal number represented in the U.S. by 1 followed by 45 zeros, and in Great Britain by 1 followed by 84 zeros.
  • rational function — a function that can be written as the quotient of two polynomials with integral coefficients.
  • recreational drug — drug taken for pleasure
  • reduction formula — a formula, such as sin (90° ± A) = cos A, expressing the values of a trigonometric function of any angle greater than 90° in terms of a function of an acute angle
  • reflection nebula — a cloud of interstellar gas and dust that reflects the light of neighboring stars.
  • regulated tenancy — (in Britain) the letting of a dwelling by a nonresident private landlord, usually at a registered fair rent, from which the landlord cannot evict the tenant without a possession order from a court
  • replacement value — insurance: sum required to replace sth
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