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数学专业英语-(a) How to define a mathematical term?" A9 `( o- A& O
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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。 ! E) D0 _% m/ ^1 m8 W
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9 Y/ @, c. l* H4 Z# h+ B 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。
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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。
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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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/ K+ \ T4 }) I7 b G; s( i& ^$ r 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?1 ` r; m) R8 e/ v% |+ j3 a( ?
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2 ~ f1 N }( { is defined as 3 J4 @+ r* m/ T3 N+ ?' c
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is called
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1. Something something , K D5 p$ o3 {/ q
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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.
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8 Z+ D6 l) J I/ P9 \# A The mapping , ad-bc 0, is called a Mobius transformation. 2 Z ?* _: @ T/ D5 u
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is defined to be
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0 V6 v" h' n5 T$ b+ B2 A is said to be
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2. Something something(or adjective) 9 H( Q c3 d! O
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- r8 b5 F9 a9 I/ `& F8 F, s The difference A-B is defined to be the set of all elements of A which are not in B. * Y0 W2 K4 M, m. c1 Z
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A real number that cannot be expressed as the ratio of two integers is said to be an irrational number. 1 r. d. E( o7 ^8 \4 d
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Real numbers which are greater than zero are said to be positive.
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; N/ m" ?% _' a define 2 N; ?2 u! w; i* M! ~
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call
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- D9 r- s7 y" q9 f! |3. We something to be something. o4 _ h8 H- m8 g: g0 y9 M: ?
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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. * {2 Z3 ?1 O, b, x& Z4 Z$ L
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We call real numbers that are less than zero (to be) negative numbers. 5 F& U. T4 P; {3 A* P( {5 b
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; c5 I- q7 }7 A" _) d 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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is called
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0 c' Q4 [3 \4 h2 j3 J is said to be
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Let…, then…
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8 z2 @4 U3 G9 j8 b! s$ H 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 . q) d, f) y6 h
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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: ' O/ `; ?7 V& {8 b2 r$ c: J* p) [
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is called
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( w/ l! w) i4 V4 O# t$ }& ^ is defined as ( k `- r0 P- N1 E9 F- M
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is defined to be
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If…, then… ' I. ?) T- ^/ _6 _5 W( f" C# ~$ o
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If the number of rows of a matrix A equals the number of its columns, then A is called a square matrix. 5 [% v8 H/ @* z
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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. . k2 Y }5 G" ?( S
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9 I, B1 P( U* B& B 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:
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is called
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Let " V. |! C! T, ~& W9 W; k6 `
Suppose | …. If…then… …
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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 Y. v# \5 A9 z! P. j. C- f
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