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17-letter words containing c, e, l, r

  • 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 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.
  • negative particle — a word that indicates negativity, for example 'not' in English or 'ne pas' in French
  • nephelometrically — By means of nephelometry.
  • neurobiologically — In terms of or by means of neurobiology.
  • neuropathological — (medicine) Of, pertaining to, or arising from neuropathology, the pathology of nerve tissue.
  • neuropharmacology — the branch of pharmacology concerned with the effects of drugs on the nervous system.
  • neuropsychologist — A neurologist or psychologist whose speciality is neuropsychology.
  • never looked back — If you say that someone did something and then never looked back, you mean that they were very successful from that time on.
  • new scotland yard — See under Scotland Yard (def 1).
  • non-controversial — of, relating to, or characteristic of controversy, or prolonged public dispute, debate, or contention; polemical: a controversial book.
  • non-materialistic — excessively concerned with physical comforts or the acquisition of wealth and material possessions, rather than with spiritual, intellectual, or cultural values.
  • non-stereotypical — a process, now often replaced by more advanced methods, for making metal printing plates by taking a mold of composed type or the like in papier-mâché or other material and then taking from this mold a cast in type metal.
  • non-thermoplastic — soft and pliable when heated, as some plastics, without any change of the inherent properties.
  • nonalcoholic beer — Nonalcoholic beer is beer that does not contain any alcohol.
  • north little rock — a city in central Arkansas, on the Arkansas River.
  • 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 isomerism — isomerism (def 2).
  • 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 submarine — undersea vessel powered by atomic energy
  • nuclear threshold — the point in war at which a combatant brings nuclear weapons into use
  • nuclear-free zone — any area in which nuclear weapons, power plants, or materials are not allowed.
  • nuclear-isomerism — Chemistry. the relation of two or more compounds, radicals, or ions that are composed of the same kinds and numbers of atoms but differ from each other in structural arrangement (structural isomerism) as CH 3 OCH 3 and CH 3 CH 2 OH, or in the arrangement of their atoms in space and therefore in one or more properties. Compare optical isomerism, stereoisomerism.
  • 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.
  • oceanographically — In terms of oceanography.
  • off-year election — (in the US) an election held in a year when a presidential election does not take place
  • official receiver — an officer appointed by the Insolvency Service to receive the income and manage the estate of a bankrupt pending the appointment of a trustee in bankruptcy
  • old norman french — Norman French (sense 1)
  • old orchard beach — a resort town in S Maine.
  • omphalomesenteric — (anatomy) Of or pertaining to the umbilicus and mesentery.
  • on cruise control — If you say that someone is on cruise control in a contest, you mean that they are winning the contest easily and without needing to make a lot of effort.
  • once over lightly — a hasty or superficial treatment, look, examination, etc.; once-over: The maid gave the room the once-over-lightly.
  • once-over-lightly — a hasty or superficial treatment, look, examination, etc.; once-over: The maid gave the room the once-over-lightly.
  • online dictionary — a dictionary that is available on the Internet or World Wide Web and accessed through a Web browser using a computer or a mobile device, primarily by typing a query term into a search box on the site. Online dictionaries like Dictionary.com offer immediate, direct access through large databases to a word's spelling and meanings, plus a host of ancillary information, including its variant spellings, pronunciation, inflected forms, origin, and derived forms, as well as supplementary notes on matters of interest or concern about how the word is used: Some people think online dictionaries will make print dictionaries obsolete.
  • optical carrier 3 — (networking)   (OC-3) A SONET rate of 3 * 51.84 = 155.52 megabits per second, which matches STS-3.
  • optical carrier n — (networking)   (OC-n) A SONET rate of n times 51.84 megabits per second.
  • optical isomerism — stereoisomerism in which the isomers are identical in molecular weight and most chemical and physical properties but differ in their effect on the rotation of polarized light.
  • oregon crab apple — a shrub or small tree, Malus fusca, of the rose family, of the northwestern coast of North America, having hairy leaves, white flowers, and yellow or green oblong fruit.
  • osculating circle — circle of curvature.
  • overreach oneself — to fail because of trying to do more than one can
  • oystershell scale — a scale insect, Lepidosaphes ulmi, having a scale shaped like the shell of an oyster, which infests various deciduous trees and shrubs.
  • palace revolution — a challenge to or overthrow of a sovereign or other leader by members of the ruling family or group.
  • palaeoarchaeology — the branch of archaeology concerned with the earliest fossil remains
  • paleobiochemistry — the study of biochemical processes that occurred in fossil life forms.
  • paleoconservative — a person advocating an older, traditional type of conservatism, especially in politics.
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