数学专业英语-(a) How to define a mathematical term?; K' T" _1 u) i9 X; ~1 U
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6 D; d9 Z; h. H" J 数学术语的定义和数学定理的叙述,其基本格式可归纳为似“if…then…”的格式,其他的格式一般地说可视为这一格式的延伸或变形。 2 W4 _: U% j9 M9 [# v7 I" b! s' g
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" y+ a+ \$ @+ A8 R) ~* g5 j$ Z 如果一定语短语或定语从句,以界定被定义的词,所得定义表面上看虽不是“If……then……”的句型,而实际上是用“定语部分”代替了“If”句,因此我们可以把“定语部分”写成If句,从而又回到“If……then……”的句型。 0 z/ e% Q5 }# U9 M3 a3 H2 |
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# F- u8 A- j4 L: s: E i 至于下面将要叙述的“Let…if…then”,“Let and assume…, If…then…”等句型,其实质也是基本句型“If……then……”的延伸。
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/ Y4 q+ t( v. U$ W! _ 有时,在定义或定理中,需要附加说明某些成份,我们还可在“if…then…”句中插入如“where…”等的句子,加以延伸(见后面例子)。
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总之,绝大部分(如果不是全部的话)数学术语的定义和定理的叙述均可采用本附录中各种格式之。 # q0 t0 g" O6 u/ B/ z+ Z
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% z$ e) U. D6 v" W( N R! J+ e (a)How to define a mathematical term?
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% X& w+ s$ `9 u- b+ u; p9 { is defined as 8 y, |$ u; t, |6 i
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* S+ m- A( z Z6 ~% ~6 x is called 9 n4 p( P: U; g( D6 ]
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% W) G. |4 X W- B- ?1 j, n5 H1. Something something
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! p- V: Y$ `. S; c" ^* m+ E2 v# r The union of A and B is defined as the set of those elements which are in A, in B or in both.
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; G9 ?: m9 L: G- D" E The mapping , ad-bc 0, is called a Mobius transformation. ( P; F2 u7 U% _7 [) E- Z
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* p( u. M4 w3 U9 k, g5 t3 Z is defined to be ) q" v7 Q: K5 g+ o
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4 q7 n( `! u/ z% t, n is said to be
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" N+ v3 b4 B8 r, A* n5 a' K1 {2. Something something(or adjective) 8 E8 _9 G) t% v* L! `) {
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: X! l4 [, T. q. ~ The difference A-B is defined to be the set of all elements of A which are not in B. ; p) D4 ~- V4 z0 E5 C7 `
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A real number that cannot be expressed as the ratio of two integers is said to be an irrational number. ' m" h& ?& x' o$ S. q9 o; Y
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Real numbers which are greater than zero are said to be positive. ) i4 I! R4 u+ X& B N" X- K( a7 g
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1 a1 X8 r/ X5 a define
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3. We something to be something. : w( _3 r5 q. c8 M4 o% B% p# f
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( x1 L; L% F6 J5 W9 i& W We define the intersection of A and B to be the set of those elements common to both A and B.
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0 \8 ~% z" `, h We call real numbers that are less than zero (to be) negative numbers.
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; K( O5 @- V2 ~# } 4. 如果在定义某一术语之前,需要事先交代某些东西(前提),可用如下形式: , r6 m2 o& ?7 ~
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' F3 s% F$ l# ^5 A is called 6 F& A2 s- k% D* T
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is defined as # _9 c) k4 I! w e/ y$ p/ N
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is defined to be , X1 F/ c& ^" o! Y2 R1 M1 W% |4 E
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0 @: m: F' w( S9 x9 y, h+ o4 V Let…, then…
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Let x=( ) be an n-tuple of real numbers. Then the set of all such n-tuples is defined as the Euclidean n-space R.
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Let d(x,y) denote the distance between two points x and y of a set A. Then the number
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3 T6 ]& ~* F3 ^; Q8 ^ is called the diameter of A. ' `5 i' n, w- }% f: Z/ w' i
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5.如果被定义术语,需要满足某些条件,则可用如下形式: 2 D; r0 P P: L5 i2 O* Q8 w
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7 z5 d' {7 l) p# S' V2 Z is called ( n/ g3 @& D$ Q: J1 p
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" C3 \2 t: z3 g+ k is said to be - T1 _4 ]: g* X+ }/ f& T K$ b
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is defined as
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is defined to be
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If…, then…
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! w1 x& V+ }# k+ n A% Q If the number of rows of a matrix A equals the number of its columns, then A is called a square matrix.
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If a function f is differentiable at every point of a domain D, then it is said to be analytic in D.
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9 ~" x% `4 m, s0 X 6.如果需要说明被定义术语应在什么前提下,满足什么条件,则可用下面形式: / F- i+ e* c4 @" z# ]6 z9 a
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9 g5 j: A" ~3 Z5 @0 _is called 7 |; g2 Q$ J" O6 o
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Suppose | …. If…then… … * E# {/ [1 i- g4 _4 k Q. P7 G2 y
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3 W! K! Z0 b: P: | Let f(z) be an analytic function defined on a domain D (前提条件). If for every pair or points , and in D with , we have f( ) f( ) (直接条件),then f(z) is called a schlicht function or is said to be schlicht in D. ; ~4 a* F9 F' {: _% j& f7 P+ b
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