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数学专业英语-(a) How to define a mathematical term?
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) W" s; Q# s) ^% Y' p 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。 ; ?5 N' Z+ I/ c( J, W
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& ?! @# `) @& Y% t5 [ 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。 ' g) T" J, @1 h1 q& I. ~
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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。 : W' e9 Z* l+ L3 ?0 d1 x- h
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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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e; U% S' y# o; I3 J: P ^ 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。 1 ?( Z) H5 V3 e2 V- k
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* j; m$ i5 {0 r (a)How to define a mathematical term?
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" R5 \& z0 q3 O/ f is defined as
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is called 4 X2 s( Z Y; }6 w4 ]
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4 M0 |) h; Y# s8 w6 `6 [1. Something something
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The union of A and B is defined as the set of those elements which are in A, in B or in both. ) Q: Q/ \0 |) s0 ~8 d
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1 h" R& o! K& m" I' v- u+ C- O) { The mapping , ad-bc 0, is called a Mobius transformation.
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$ @% |8 f9 n- T% D& W& | d is defined to be 6 U5 I' R- ~7 O+ n1 Z- r
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is said to be . s3 C+ E; j3 ^
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0 Q+ B0 @; u! _2. Something something(or adjective) 6 Z6 J2 i/ n- N/ P6 c' `' \ u& i- e
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) T- N5 g! u( I. i1 k. X* C* L7 p The difference A-B is defined to be the set of all elements of A which are not in B. 9 l5 d, N% X: v" J
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. N: z# @3 R* h* b3 o3 m A real number that cannot be expressed as the ratio of two integers is said to be an irrational number. ! f7 W0 b% t2 N5 X! w8 X9 A6 m
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5 w) U5 w6 V" P7 F9 K Real numbers which are greater than zero are said to be positive. $ g$ m o- t5 i2 o/ b R( W
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4 r- p! r( `( j! W( u3. We something to be something.
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7 {7 C: {% d6 l2 p5 v: ] t/ Q 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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( n6 S/ d( b) n) ~/ T# w We call real numbers that are less than zero (to be) negative numbers. & V0 R% ^9 L: x! G
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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:
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0 o% t& b! w$ r" i2 F! c is defined to be 2 Y; u6 C; P: P3 b
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Let…, then…
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4 k$ m. u, S6 e& Z7 P# n L 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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is called the diameter of A.
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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: + F5 l0 n" D- `/ [. h( P- K
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is called
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is said to be
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is defined as
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; a M4 S' s7 ]& ^; T is defined to be
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If…, then… ; x* Z7 j; e9 z2 ]8 q
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- h6 L+ P$ K8 ^+ F+ E If the number of rows of a matrix A equals the number of its columns, then A is called a square matrix. ; ^. m+ ~0 x! }& W
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$ Q; c9 @; x+ M7 U- y ~4 k O 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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! z' `4 C, q# _+ S1 z/ N: s' F 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: 4 y, X5 c& @; u5 J" A1 i
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. m9 j/ Q" `( w5 y: L6 NLet " I( n p* F: l) P' v
Suppose | …. If…then… … # W. ?/ ^/ ]( O m
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! O% J) s4 F! { 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. / b4 t% d; h& I: _9 Y+ D* h- {
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