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数学专业英语-(a) How to define a mathematical term?8 ?4 Q: Y" e* i; I9 {5 f
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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。 % g2 j5 t) x0 C9 G4 z% H7 v
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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。 8 D f( z" K" Q; j/ y/ Y! T' M
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7 c- I# |3 \; ^6 L 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。 8 b4 N5 O, T8 L4 ?
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) T! H0 b: n. ?+ t" c, Z$ Y# r 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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+ K. q2 {0 H. n0 M 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?& a% Y7 D8 ~" t2 O+ Y. Z4 ]
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is defined as
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; |/ U& v6 h2 X3 ? is called
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7 Q3 p, g1 g9 i1. Something something 2 w$ Y- x# W) f# ?) A& J
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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 i$ R% w: y! U! Z$ f
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is defined to be
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is said to be
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2. Something something(or adjective) % v [; d0 ]5 W% t3 e' m; ^
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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 z& Q' k$ [# J4 S9 |5 o
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A real number that cannot be expressed as the ratio of two integers is said to be an irrational number. : G2 ]( l# e9 j9 k# s& E" J \) R1 _* j
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% E; C y- r9 c$ v/ X! d Real numbers which are greater than zero are said to be positive.
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3. We something to be something. & |+ I! u1 D- P, s7 j$ g* q
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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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We call real numbers that are less than zero (to be) negative numbers.
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5 G+ L) h+ E# J4 p 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 ! ~# }: z8 n& \. H9 A' `4 E
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is said to be
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4 Q# c. _$ g- a7 a4 ?* Y* b is defined to be
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Let…, then… 8 `; i9 Q- K% A- `( u- |
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1 e L& ^& s. y: C% A: 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.
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0 X& D) O6 p0 q; ?( e! p6 i& _. b: \ Let d(x,y) denote the distance between two points x and y of a set A. Then the number
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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: & F/ Z' \1 U& u: O) q8 }
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is called
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is said to be - a! z9 t, T9 ^ _# W. ]4 W. B/ z6 s
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If…, then…
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6 u2 l& c! N5 x' z" b If the number of rows of a matrix A equals the number of its columns, then A is called a square matrix. # k1 m Q! |' G( o X
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3 P8 ~1 k7 u5 r) O3 ?: G6 v U 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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3 I! {$ a9 i9 S) s; ^% } 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: ' a- v- S1 L$ ]. h$ T- G
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Let * k: ]3 `7 p x
Suppose | …. If…then… …
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) e4 x+ T0 o+ Q; }! C 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. 8 |# Y; R% j9 L
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