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数学专业英语-(a) How to define a mathematical term?
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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。 5 ^- v2 T* I% c% m9 K: G& {
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, X$ r7 W z" D' 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。
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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)。 , d0 i @7 ^$ A% j
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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?+ H) S8 z3 b( {; V! k! d& S
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; Z8 J- u0 d; Z6 u3 i1 o2 \1 @% ~7 _ is defined as . N; m4 Z5 i: B* ?
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1. Something something
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4 b4 @$ ~/ Z4 h) e9 w4 O f- e9 ` The union of A and B is defined as the set of those elements which are in A, in B or in both. 8 V, S0 ?0 t& s% z' ~: N
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The mapping , ad-bc 0, is called a Mobius transformation. ) E7 V9 l$ b4 L- c& ?
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is defined to be s# G, ^9 b5 ?, q9 U0 P
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is said to be
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. M+ D+ H; B2 b2. Something something(or adjective) ) U5 q8 H+ h3 w9 t! L& Y" u: H3 R
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The difference A-B is defined to be the set of all elements of A which are not in B. 7 L5 H! H/ }/ p6 {0 X
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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. 6 E: o; _* @/ _5 g; q
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call
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3. We something to be something. ; |! ^0 H2 i3 d/ W+ ~) o5 b& `5 i
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- I+ _! A- T5 }8 ` w$ q1 W' C 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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( v% s0 p! U6 P+ F6 A8 U We call real numbers that are less than zero (to be) negative numbers.
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. C) m3 W5 X9 x, U5 _ 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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5 |* g2 J6 p. Z; ~ is called 9 |* G$ ~7 l0 s" C' {+ j
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is said to be
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; ?8 F+ |, g, `( G7 y0 r is defined as
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is defined to be 4 B2 P' x/ _8 [
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7 Z. J* D4 V q( S Let…, then… 0 X8 e1 A" h2 K( a
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, v* W7 E- C. P& r/ K 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. ( q- G: I) O% _0 }8 D
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! O" C& y \# c3 `4 O Let d(x,y) denote the distance between two points x and y of a set A. Then the number
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D=
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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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# M8 l8 [( i- v6 E8 e is called . i* G8 e$ x/ b" u1 d3 X# X
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is said to be [4 |" [, s0 Z
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! T q, R' R; q, h/ b is defined as
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. j: C$ Z( o$ k9 ?6 B' d If…, then…
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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. " {# Z7 X" @ U& C
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8 C& f6 _. [5 z5 m S If a function f is differentiable at every point of a domain D, then it is said to be analytic in D. c% A0 {6 n" |+ N
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- N" X; }7 Z: d0 X8 L 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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: }. \! A4 n- j1 }is called
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Suppose | …. If…then… … / @7 k ^" R. y) T" ?3 Z- Z$ _4 K
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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. 3 Y4 U2 x( ?7 @4 l A; I
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