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数学专业英语-(a) How to define a mathematical term?
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% S1 Q: Y+ P! `# h4 V/ V+ |/ s+ [. K 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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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。 - |+ d) `) q) ]
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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)。 - i4 i" C& m) t- \) j
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! o+ j& a7 L3 L0 Q 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。 4 S5 G3 D3 A' F
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7 i) D* ` w; `5 N5 h6 V4 A$ { (a)How to define a mathematical term?
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is defined as
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0 x4 \8 l# h/ e& t is called
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1. Something something 3 r6 M( Q0 A, h
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4 D4 t6 _3 v6 m' |" W' i 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. $ c. G: y8 D& Z8 L8 E/ d
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is said to be 2 N% F* \- s7 n
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2. 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.
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A real number that cannot be expressed as the ratio of two integers is said to be an irrational number. 6 h3 ~% z( t+ H. ^) F6 n
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; g6 ? G3 [" j Real numbers which are greater than zero are said to be positive. 5 v* o) x7 w3 ^! [$ F! c
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define 1 V% S. Q- g/ G2 T5 ]
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call
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: {6 e/ F. y' _3. We something to be something.
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+ d( T) O0 f1 b' m! x$ |5 H We define the intersection of A and B to be the set of those elements common to both A and B. . |; x- d1 R; O1 i' Z
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We call real numbers that are less than zero (to be) negative numbers. + L7 m; a/ q S2 R3 ? S
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4 z! f+ b% H- e4 H& b 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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is defined as
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is defined to be , a6 t% g/ [9 O- C R' Z
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4 f# @# [+ P7 t3 _6 L4 D% Y& S Let…, then… ( S. Q% q4 P1 y. @% s
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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.
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$ B/ m& n, `# F. \5 d( }1 }. b Let d(x,y) denote the distance between two points x and y of a set A. Then the number 8 h! j- U0 \/ Q, m* K! F9 V: e
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, i6 q8 B# e3 W7 D3 U9 B6 q, W is called the diameter of A.
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' V0 B8 o& ~9 q( z& I5 } 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 ( P8 i; v4 d; i8 q3 d! q! D0 K& U. R
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is said to be
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is defined as
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; W, s2 ]6 X! [+ S is defined to be
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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.
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9 m- X7 w9 i( k5 T; @ If a function f is differentiable at every point of a domain D, then it is said to be analytic in D. 4 m( R4 _: C, ~0 H# T7 [
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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: 2 N1 T: K) s$ Z+ h5 r! Z: V
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is said to be |
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Let
' V7 U/ g1 i1 r- O0 Z) V. k5 }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. # \* P% l$ _. X
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