| 释义 |
▪ I. dual, a. (n.)|ˈdjuːəl|
Also 6 douale, 7 duall.
[ad. L. duāl-is containing two, f. du-o two: cf. F. duel, and see -al1.]
A. adj.
1. Of or pertaining to two. dual number (Gram.), the inflected form expressing two or a pair.
1607Bp. Andrewes Serm. II. 217 In the holy tongue, the word which signifieth life is of the dual number. 1706A. Bedford Temple Mus. iv. 75 It ought to be read..in the Dual or Plural Number. 1876J. Parker Paracl. ii. Epil. 397 The great dual law which makes Adam and Eve one humanity, the dry land and the seas one globe.
2. Composed or consisting of two parts; two-fold, double.
1654H. L'Estrange Chas. I (1655) 7 His Majesty..conducted her to Canterbury, where the marriage was finally completed..From Canterbury his now dual Majesty took coach for White-hall. 1862Weldon's Register Aug. 3 That in the dual life of man the working faculty should be married to intellectual beauty. 1871Tyndall Fragm. Sc. (1879) II. vi. 79 Truth is often of a dual character. 1886Pall Mall G. 1 Dec. 3/1 They..proclaimed it as their policy to get rid of this ‘dual ownership’ in the land. 1891Daily News 15 Apr. 6/4 The skirt was dual, and rather short.
3. In specific collocations: dual carriageway, a road with separate carriageways, divided by a central strip, for up and down vehicular traffic; dual control, control exercised by two parties or persons jointly; in Aeronaut., the duplication of the pilot's controls for instructional purposes; similarly in a motor vehicle; freq. attrib.; hence dual-controlled adj.; dual ignition, ignition in a motor-vehicle engine by two independent currents from a battery; dual key, a system of joint control over the use of nuclear weapons deployed by one government in the territory of another, allowing the weapons to be fired only if both governments have given permission; freq. attrib.; dual personality, two distinct personalities in one individual; dual-purpose adj., serving two purposes or bred for two purposes; spec. of cars, capable of carrying people and goods; dual-standard adj., pertaining to or capable of transmission or reception of television programmes using either of two different picture-densities (see quot. 1961).
1933Proc. Inst. Municipal & County Engineers LX. iv. 274/2 The intention of such roads was to so design them as to enable them to carry very fast traffic safely. The only method of doing that was by providing dual carriageways with central strips which could be so treated as to make them a delightful amenity. 1957I. Murdoch Sandcastle viii. 128 A dried-up grass verge separated her from the dual carriageway. 1968Dual carriageway [see blub n.].
1884Illustr. London News 23 Feb. 170/2 The Dual Control{ddd}was the proximate cause of our troubles in Egypt. 1913Captain Sept. 1069/2 Military influence is seen in the two or three-seated machine with dual control. 1914Aeroplane 15 July 60/2 Even if the ‘Herring Pond’ is crossed previously by a single or dual control machine. 1944H. C. Dent Education Act, 1944 21 The compromise on the ‘Dual Control’ of schools is one of the outstanding triumphs of the Act. 1959Which? May 37/2 All lessons should be on a dual-control car.
1930Daily Tel. 24 July 10/4 The machine was dual-controlled.
1909Westm. Gaz. 22 July 8/3 Some system of what is known as dual ignition for the modern high-class..motor-car. 1917A. G. Clark Text Bk. Motor Car Engin. II. 73 Having in view the high efficiency of the modern magneto, it may be accepted that the dual ignition will only be fitted on the more expensive and high-powered cars to facilitate starting up.
1979Economist 27 Jan. 41/2 American cruise missiles could be put into Europe under dual-key control. 1980Hansard Commons 17 June 1353 We could have a dual key if we shared in the cost and the ownership of the weapon, but we do not. 1981R. United Services Inst. Jrnl. June 5/2 Various systems equipped with US nuclear weapons and operated on a dual-key basis. 1983Daily Tel. 15 Feb. 2/3 The controversy over ‘dual key’ continued yesterday despite Mr Heseltine's assurance that, without such an arrangement, Britain could still prevent American Cruise missiles being fired from bases in England.
1905Strand Mag. Apr. 451/2, I feel my dual personality rather puzzling. 1917A. Waugh Loom of Youth i. ii. 29 In the corps as Officer Commanding..and as a clerk in orders... His dual personality embodied the spirit of ‘the Church Militant’. 1935B. Russell Relig. & Sci. v. 140 In cases of what is called dual personality..what seems to outside observation to be one person is, subjectively, split into two. 1958‘Lancaster’ & Poling Strangers in my Body iii. 128 This twenty-five-year-old married female patient was referred for psychological examination with diagnosis of dual personality.
1914Scotsman 8 Oct. 9/1 The number of ‘dual-purpose’ boats, equipped to burn both coal and oil, includes 38 battleships,..and 21 light cruisers. 1925J. T. Cole in G. F. Finlay Cattle Breeding ii. xxxii. 431 The ‘dual-purpose’ Shorthorn type imported from England in the first half of last century. 1958Observer 19 Jan. 5/4 Police action against owners of ‘dual purpose’ cars has increased sharply. 1958Church Times 21 Nov. 1/2 He saw St. John's—at present a dual-purpose hall which is also dual-owned, the sanctuary belonging to the diocese and the hall to the local authority.
1961Which? Nov. 301/2 A dual standard (sometimes called switchable) set, which operates at present on the 405-line system, but which is already partly converted and might need only a new tuning unit to make it capable of receiving both 405 and 625-line transmissions. 1965B.B.C. Handbk. 111 A new television studio in Glasgow and a modified one in Bristol are equipped for dual-standard working.
B. n.
1. Gram. The dual number.
1650Reeve Introd. Grk. Tongue 9 In the second and third duall, and in the second plurall. 1832Coleridge Table-t. 7 July, It is very natural to have a dual, duality being a conception quite distinct from plurality. 1858Max Müller Chips (1880) III. i. 3 Gothic. (where we still find a dual in addition to the singular and plural).
†2. App. a name for the two middle incisor-teeth in each jaw. Obs.
1541R. Copland Guydon's Quest. Chirurg. (1579) 18 Howe many tethe ought euery persone to haue?.. In some is founde .xxxij .xvj. in euery Jawe. And in other is founde but [x]xviij. That is to wyt two douales two quadruples .viij. molares and two cassalles [orig. L. duo duales: duo quadrupli: et duo canini: et viii. molares et duo caysales].
3. In chess problems, a choice in White's continuations. Hence dual v. in pass., to admit of a dual solution.
1875City of London Chess Mag. 116 The Black Pawn on the K R file is here omitted as superfluous, and the above-mentioned duals entirely eliminated. 1903Daily Chron. 11 July 8/7 Your problem is dualled by 22 17. 1906A. C. White Tours de Force p. xxxiii, If White is allowed a choice of continuations, such a choice is called a dual, or multiple, continuation. There are two kinds of duals: Absolute duals..and minor duals. 1966New Statesman 13 May 705/2 That beautiful piece by Sikdar..had to be disqualified because a dual was discovered and couldn't be cured.
Sense A. 3 in Dict. becomes A. 4. Add: [A.] 3. Math. a. Of a theorem, etc., in projective geometry: corresponding to some other theorem, etc., by the interchange of certain pairs of terms, as ‘point’ and ‘line’, ‘lie on’ and ‘pass through’. Const. to.
The concept was earlier designated by the term reciprocal (see reciprocal a. 3 a).
[1873J. Booth Treat. Geom. Methods p. xiv, As the properties of space are dual, so must the systems of investigation be dual also. 1877Encycl. Brit. VI. 719/1 Plücker first gave a scientific dual definition of a curve.] 1910Veblen & Young Projective Geom. I. i. 27 Dual to the class of all planes on a line we have the class of all points on a line, i.e. the line itself. Ibid. 29 He should..state both the original and the dual proposition in the ordinary terminology. 1929Encycl. Brit. XVIII. 573/1 After the principle of duality in the plane has been comprehended it is necessary only to state one of each pair of dual theorems. 1940J. L. Coolidge Hist. Geom. Methods ii. ii. 145 The whole volume is largely devoted to theorems which are dual to those already developed. 1989W. Gellert et al. VNR Conc. Encycl. Math. (ed. 2) xxv. 553 To every theorem of projective geometry there is..a dual form, whose proof follows from that of the original theorem. Ibid. 555 The theorem ‘A point and a line not through it determine exactly one plane’ has the dual form ‘A plane and a line not in it determine exactly one point’.
b. transf. Designating other pairs of entities related to each other by an interchange of certain components (e.g. vertices and edges in the case of maps and networks).
1947P. A. M. Dirac Princ. Quantum Mech. (ed. 3) i. 18 Whenever we have a set of vectors in any mathematical theory, we can always set up a second set of vectors, which mathematicians call the dual vectors. 1971G. Glauberman in Powell & Higman Finite Simple Groups i. 54 The group dual to v is the group v*. 1977Sci. Amer. Oct. 112/3 He began by transforming the original map into what mathematicians call a dual form: a planar graph in which each vertex of the graph represents a country and each line segment between vertices represents a border. 1979Page & Wilson Introd. Computational Combinatorics iv. 57 The 3-combination (2 6 7) could be represented by the binary number 01100010... If we interchange zeros and ones we have the combination (1 3 4 5 8), sometimes called the dual combination. 1980A. J. Jones Game Theory iii. 119 Corresponding to any linear program, there is a related linear program called the dual program.
[B.] 4. Math. A theorem, etc., that is dual to some given theorem, etc.; any dual entity.
1910Veblen & Young Projective Geom. I. i. 29 It is highly desirable that the reader gain proficiency in forming the duals of given propositions. 1947Courant & Robbins What is Math.? (ed. 4) iv. 191 The dual of any true theorem of projective geometry is likewise a true theorem. 1967A. Battersby Network Analysis (ed. 2) xi. 178 The dual of a network is drawn by connecting the spaces enclosed by it. 1972Sci. Amer. Mar. 124/3 You will find..figures named after Archimedes, with mixed faces but identical corners. With them, as with the solids of Plato, you can build the duals: replacing corners by faces and faces by corners. 1980C. S. French Computer Sci. xxii. 144 If you take a true relation and convert all ones to noughts, all noughts to ones, all ANDs to ORs and all ORs to ANDs you will obtain the dual of the relation. The dual will also be true.
▸ dual-band adj. designating telecommunications and broadcasting systems capable of operating in or receiving either of two different frequency bands, spec. two of the microwave bands used for satellite communication.
1932N.Y. Times 18 Aug. 41/1 The *dual band design of the transmitter used on the new ships was dictated by the results of important research. 1954Times 23 July 9/6 (advt.) 12{pp} dual-band table model with Bush Auto-control of both vision and sound. 2001Contact May 54/3 The SL45 is dual-band, has a screen big enough to make the most of the WAP browser, and features all the usual mobile phone functions.
▪ II. dual, v.|ˈdjuːəl|
[f. the adj.]
trans. To convert (a road) into a dual carriageway.
1959Times 23 Dec. 4/2 Before 1958–59, 20 miles [of the Great North Road] were already dualled and during the year a further 24 miles were completed. 1961Times 15 Dec. 8 (caption) Trunk road to be dualled in the current programme. 1969Oxford Times 18 Apr. 17 (heading) Northern by-pass to be dualled to Banbury Road.
▸ trans. U.S. In the motor industry: to authorize (a dealership) to sell two (or sometimes more) brands of vehicle. Usu. with with. Also intr. Cf. dualling n. 2.
1957Washington Post 6 Jan. k18/4 Packard and Studebaker dealers have been dualed..not only to broaden the distribution base..but also to strengthen individual dealers by giving them a wider price range in which to market. 1961P. Pashigian Distribution of Automobiles iv. 118 When it is in the interest of the manufacturer to dual, for example in small markets, dualing is permitted. 1981N.Y. Times (Nexis) 8 Mar. v. 10/1 So many domestic dealers are dualed with imports. 2002Ward's Dealer Business (Nexis) Aug. 12 Land Rover plans to increase its dealerships to 200 over the next few years, says Williams. Many of those stores will be dualed with the Jaguar brand.
▪ III. dual(e
obs. form of dwale. |