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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。 4 e7 f6 d( u% {5 v
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6 W- i$ B, j7 c( i# t 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。 1 m: O- B4 t2 G+ \
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- K6 g3 }" D2 k0 c3 i6 q 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。 1 D) a7 j, Y3 n% J/ a) a
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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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7 Q7 |/ G/ Y! `% Y 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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( P$ ^& K) X7 z7 @. Z (a)How to define a mathematical term?" Z! T0 g3 K, x) S2 Z! e" ~. l
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is defined as % O0 X* }( f: l5 A
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! s9 V& x- G4 X+ i# Z$ f8 o1. Something something 4 K* ?, ~( }" N$ n( ]. ?
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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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The mapping , ad-bc 0, is called a Mobius transformation. 9 W/ ], O% f6 c, s9 ^6 ^
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/ y6 E% o0 B- b5 B8 r& | is defined to be
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is said to be
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2. Something something(or adjective)
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. a: m+ C' `9 s+ Z2 B' c The difference A-B is defined to be the set of all elements of A which are not in B.
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A real number that cannot be expressed as the ratio of two integers is said to be an irrational number. 5 _1 \! Y2 Q S: g
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Real numbers which are greater than zero are said to be positive.
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2 u4 ^6 _" d2 U/ E0 e ]5 @ define
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3. We something to be something. 8 S: C l3 p; k* l/ @: j# T) b! b
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, y' Q, |6 Y2 f& T3 _0 n; D We define the intersection of A and B to be the set of those elements common to both A and B. 8 s* g: ]! v) K7 j [* a
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1 T4 c- K( }# n0 _. e We call real numbers that are less than zero (to be) negative numbers.
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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: + d) L4 U' S, c
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is called 2 @6 y% i. _$ s. A9 E3 T' B+ H3 ^8 }3 b
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1 d( V1 E- F% r3 V: D is defined as
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& D8 @2 X" F: F7 v1 u& _ Let…, then…
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5 J# ?, U7 v8 C, N( ?& q$ Z# o; g 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. 9 R4 q- F; D0 w
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) m+ A1 o7 T0 j, L0 _6 e Let d(x,y) denote the distance between two points x and y of a set A. Then the number
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7 t9 L. v# z' L) {2 R p 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 , s* r8 ^0 L4 Q0 G( ^( p8 P; |
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is said to be 4 A' z- h9 P$ n
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is defined as
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is defined to be
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h: k; L% b7 V c$ F If…, then… 9 {1 S9 W5 a/ w( Q; Q" T
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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.
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* b4 j% x ]6 G; i) k% C If a function f is differentiable at every point of a domain D, then it is said to be analytic in D. , z0 |+ j a; d* I( m8 ?8 G4 y( t
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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:
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x, @* i- ~0 X6 W L2 ?is called
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Let * @, n: F2 ?! Z( u
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. 3 ^' z6 n. W' D- N- o' E) U
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