| 释义 |
alternation|æltəˈneɪʃən, ɔːl-|
[a. Fr. alternation, ad. L. alternātiōn-em, n. of action f. alternāre: see alternate a.]
1. a. The action of two things succeeding each other by turns; alternate succession or occurrence.
1611Cotgr., Alternation, an alternation, a succession by turne. 1646Sir T. Browne Pseud. Ep. 147 Hares may exchange their sex, yet..not in that vicissitude or annuall alternation as is presumed. 1766Goldsmith Vic. W. (1857) 242 My spirits were exhausted by the alternation of pleasure and pain. 1866G. Macdonald Ann. Q. Neighb. xxi. 394 She behaved with strange alternations of dislike and passionate affection. 1880H. James Benvolio i. 345 To take the helm in alternation.
b. alternation of generations: = alternate generation; see alternate a. 2 b.
1858Lewes Sea-side Stud. 287 The solitary Salpa produces the chain-Salpa by ‘budding’; and the chain-Salpa by ‘alternation of generations’ (the phrase is Chamisso's [1819]) produces the solitary Salpa by ova. 1875Bennett & Dyer Sachs' Bot. i. iii. 203 When alternation of generations occurs, in certain cases all the alternate generations may be asexual. 1881Lubbock in Nature No. 618. 404 In 1842, Steenstrup published his ‘Alternation of Generations.’
2. The action of taking the individuals of a series alternately.
1695W. Alingham Geom. Epit. 100 For if A:a::B:b, Then by Alternation A:B::a:b.
3. Successive change in a scene or action by the alternate occurrence of phenomena.
1633T. Adams Comm. 2 Pet. i. 19 (1865) 196 By the vicissitude of time, and alternation of the wheeling heavens. 1791Hamilton tr. Berthollet's Dyeing I. Introd. 35 Inequalities in the alternation of the action of the liquor. 1845Ford Handbk. Spain i. 46 Love is..an alternation of the agrodolce. 1868G. Duff Pol. Surv. 75 Some of these provinces consist almost entirely of alluvial plains, but the greater number exhibit an alternation of fertile river valleys.
4. The position or state of being in alternate order.
1830Lyell Princ. Geol. (1875) I. i. iii. 53 Alternations were rare, of marine strata, with those which contain marshy and terrestrial productions. 1841J. Trimmer Pract. Geol. 182 Rarely met with..without the alternation of other rocks. 1860Maury Phys. Geog. Sea ii. §128 Streak after streak of warm and cool water in regular alternations.
5. The doing of anything by two actors by turns, alternate performance; reading or singing antiphonally.
1642Milton Apol. Smect. (1851) 313 Such alternations as are there [in the Liturgy] us'd must be by severall persons. 1795Mason Ch. Mus. 130 (T.) The words are not confused by perplexing alternations.
6. erron. ‘Sometimes used to express the divers changes, or alterations of order, in any number of things proposed.’ (Chambers.) Permutation.
1751Chambers Cycl. s.v., How many changes or alternations can be rung on six bells.
7. a. Logic. The truth-function that has the value ‘true’ whenever at least one of its components is true, or that has the value ‘false’ only when every component is false; the function that is usually symbolized by ‘v’ (L. vel) and corresponds to the inclusive sense of the word ‘or’ that is sometimes rendered by ‘and/or’.
1874W. S. Jevons Princ. Science: Treat. Logic I. v. 81 We require a sign of the alternative or disjunctive relation, equivalent to one meaning at least of the little conjunction or so frequently used in common language... In my first logical Essay I..adopted the common sign +; but this sign should not be employed unless there exists exact analogy between mathematical addition and logical alternation. 1890E. E. C. Jones Elem. Logic 120 Mill, and Jevons..insist upon the non-exclusiveness of alternation. 1940W. V. Quine Math. Logic i. 12 Alternation—composition of statements by means of the connective ‘or’. 1955A. N. Prior Formal Logic i. 8 Writers who use ‘disjunction’ in this way generally call the non-exclusive ‘Either p or q’, the ‘alternative’ function or ‘alternation’ of its arguments... The alternation of two propositions is also often called their logical sum.
b. A compound statement or formula formed by joining two or more statements or formulas by the connective symbol ‘v’ or the word ‘or’.
1894J. N. Keynes Formal Logic (ed. 3) ii. ix. 231 To deny an alternation is the same thing as to affirm a conjunction. 1950W. V. Quine Methods Logic (1952) i. 19 ‘Either’ and ‘or’ may be used to mark the boundaries of the first component of an alternation. |