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数学专业英语-(a) How to define a mathematical term?& u3 f/ t9 @7 b! p+ s. I9 c; v6 m
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. u: K/ j( t, P 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。 6 \( ~& N; T/ M$ M z( w6 e
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2 O8 S8 Y [( |; z/ E 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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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?/ T& x" Y# @# X( p7 Y) S8 y
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is defined as
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is called ( q5 Q8 _; C' I" A& d9 l- I2 W3 C
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8 R8 b8 B* m/ D- s; C+ b1. Something something
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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. 6 o1 H1 R/ P% H3 j# G
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The mapping , ad-bc 0, is called a Mobius transformation. " P8 G6 ~; `! `& `; n4 E P0 M
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* X% v) t% ~4 [1 i is defined to be 3 W; U) ]6 q6 }" W/ t
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is said to be M" L7 g6 ^7 F" X' }; a* i
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The difference A-B is defined to be the set of all elements of A which are not in B. 8 g! G. J& h J, q& e: h
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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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' z( }8 B2 Z+ {0 g A Real numbers which are greater than zero are said to be positive. : y/ c* ? i% ?: r" P
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* x: B# X& I$ q define
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& R. I, I- b. Y! T* O8 R3. We something to be something. , W7 s B% h3 Z+ `0 o
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! c8 U, c% T. h6 K2 a We define the intersection of A and B to be the set of those elements common to both A and B. 0 g6 B- C4 h6 ?. P; q
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; W8 \4 Y) A- S) {' j We call real numbers that are less than zero (to be) negative numbers. , j7 i( W: g) g* k- n. O6 h3 B* p* o
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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: 9 a4 v4 w( G% d+ S
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is called
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is defined as
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3 n9 ^0 H4 {% b' V4 D is defined to be
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Let…, then…
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+ Y- M5 T' n. ]0 a: }" N 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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4 O) s& K0 w1 J Let d(x,y) denote the distance between two points x and y of a set A. Then the number ; V. X7 s' }, C
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D=
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is called the diameter of A. * }" [ b) k$ ?+ b) B( ^2 T
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+ G l! k) P2 |0 T. B 5.如果被定义术语,需要满足某些条件,则可用如下形式: 1 M# J& F' ~4 O) y- W% C: J8 ^3 t) c
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+ C d% H+ z; [+ i" k# s is called
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is said to be 9 M+ C3 k8 g5 L' u; N9 ?+ j
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" x6 k/ T2 M* g) u3 G- Q8 U is defined to be 3 {, X% e! h; Y' K
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If…, then… / A' ~% p% ?4 f1 Q. X, N
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! d4 A' m& E k3 Y. F 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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# r% P, |/ x; B2 ] 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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. Y0 [ ^. E! A4 C1 v8 \# kis called
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" N# d' T5 B% QLet 0 _& C( j- z8 H/ P' t; O
Suppose | …. If…then… … , [% U" g8 s. p# d; N* }
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- P% \/ |% E- ` 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.
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