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数学专业英语-(a) How to define a mathematical term?0 R2 F- c f9 O+ W) w
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1 }" S8 T( `+ _! j8 | f 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。
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6 L. q+ x( Y, C" { 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。 ; n1 }/ y$ s# U7 e, p
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. I+ d0 p' M U$ J 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。 ) U& ^, H; n) I3 R2 w _
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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)。 9 o$ s5 t! E1 [) N
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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。
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(a)How to define a mathematical term?
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6 ~& z; o1 m$ G3 u is defined as
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is called 5 F5 {/ q# l2 r: w
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1. Something something 8 ~$ g; K2 y9 h; V- s3 M0 e
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" x) G& N" C1 W- x 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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The mapping , ad-bc 0, is called a Mobius transformation.
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+ n3 J- \: _8 v; w( T is defined to be
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. o4 K+ t! D b- G6 e R9 {$ N) U2. Something something(or adjective)
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The difference A-B is defined to be the set of all elements of A which are not in B. + w5 n% t. z& h5 ~
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A real number that cannot be expressed as the ratio of two integers is said to be an irrational number.
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Real numbers which are greater than zero are said to be positive.
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define 0 n% H- S, P3 _5 k; C
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call / z8 \% O& R0 r( [5 T
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" G8 w: U: W3 E4 N9 l3. We something to be something. 2 W) i% F7 K& b/ g( }" E
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We define the intersection of A and B to be the set of those elements common to both A and B. , L w2 b1 K' w( l+ b6 u
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# P9 E% i2 C% N+ X/ |$ U We call real numbers that are less than zero (to be) negative numbers. $ U6 m$ X+ F* ]+ K& ]$ W
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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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B3 F0 M4 R+ e$ J0 E1 w, Q is called
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is said to be
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is defined to be
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3 \% L$ Z2 P) o% g9 }: m 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. # N- y5 J% m/ ?, B$ U9 r5 w s5 g
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Let d(x,y) denote the distance between two points x and y of a set A. Then the number ( m! c, ]# p6 U5 a7 |, x7 F
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D=
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is called the diameter of A. $ d: Q$ `7 s s- q! f* F, L; A1 |9 o- Z
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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:
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is called ( _/ E# j0 A, {
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is defined as
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! j0 y0 ~" ]! c- A/ R# x) o# Z is defined to be
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If…, then…
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2 }% m& |/ ]1 A8 [+ ?8 {$ s5 N; \! p If the number of rows of a matrix A equals the number of its columns, then A is called a square matrix. ' _ N/ C' [! \& j. d9 _: N
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4 C( u/ ^, h7 Y1 |. P1 ?% O/ v 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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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: 1 N$ o2 l- X; x* R; V4 j R
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is called
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Let 0 f# d$ Q3 J ~* y0 E
Suppose | …. If…then… …
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