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数学专业英语-(a) How to define a mathematical term?( v/ h9 \, S/ Y4 w
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. P. v, n# G k" z$ z 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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. A" t) W# X5 j* c1 o 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。 / i: R7 ?9 U- [ x2 K3 `8 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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; d. B/ r2 [* }5 M3 @8 J* _ 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?
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9 R" J p4 n W$ m is defined as
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/ b, j: c" r* N1. Something something " g/ L. U+ s% F, a6 M4 O: g$ y, c
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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. 6 w5 h+ W$ f0 R# ]+ W
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is defined to be
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. q2 T( x0 N& {1 G% B& m is said to be
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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. 4 S+ @. w) W8 V% A/ ~: {. n. q
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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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+ `0 `, r, }; j# G* y) D8 J+ _ Real numbers which are greater than zero are said to be positive.
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define
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3. We something to be something.
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I# ?6 b" O0 L We define the intersection of A and B to be the set of those elements common to both A and B. ) F! L H5 `1 A
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We call real numbers that are less than zero (to be) negative numbers. 7 e% L4 c ] @0 U4 r% g: ?) _4 N& X
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3 h- B+ i' {, _ a 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 said to be O: Y; q5 b6 \( Q& `* M1 ~" m
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is defined as
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is defined to be
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Let…, then…
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0 J, u+ g8 O9 a 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. % l. n8 w: l; X
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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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is called the diameter of A. . P" a, r% s% o( p5 U" y2 X
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$ n( `+ K) [- i# J 5.如果被定义术语,需要满足某些条件,则可用如下形式: & m) c* M* M9 z3 g
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is said to be + a5 ^" S! P7 h! a% N
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is defined as
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is defined to be . I) L4 T2 e' Z2 x/ g
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$ S$ R2 c0 b6 ]/ n U& h If…, then… . A" s% ^. l+ A W* q9 T( ?, l- ^+ E. i: [
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; W# _8 M& c% W1 X If the number of rows of a matrix A equals the number of its columns, then A is called a square matrix. 0 H+ X! A4 t/ @* b; j ~
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' i4 ~4 E# L) Z+ X3 R5 H If a function f is differentiable at every point of a domain D, then it is said to be analytic in D. 2 w4 g! z. U3 s8 W/ x! x V( n% W
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" K5 `, B8 \( Z( @, O! t 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 . N) @% n& _- k' j( T2 q! I
is said to be | 1 E' i- E# P$ p; u1 e5 ~1 Y
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" Y$ g9 a4 I% g5 O) G8 b" e3 @- rSuppose | …. 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. * c, Y" n5 ?/ a$ ^" |* t
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