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数学专业英语-(a) How to define a mathematical term?. m+ d8 {6 w* i6 J1 o3 z/ \
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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。 9 t. j3 j r1 n$ v: x0 O2 x
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- D7 e: O1 G! h9 Q! N* N, j 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。 7 Y" |0 g- d7 m" V3 B7 d& d
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( \) n* i6 _8 @; b& |5 n 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。
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; b7 D; F+ a0 h5 |/ J2 q 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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6 O7 W; W$ t7 D$ G" {; g1 { 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。 , e: L/ r; j% O8 j0 ^
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(a)How to define a mathematical term?
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is defined as ! y' ?( U' q5 Q# U
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is called
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1. Something something , H$ j& Q4 i& I% ]0 O
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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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& d1 C7 h' j* v The mapping , ad-bc 0, is called a Mobius transformation. $ U9 V, d; c5 j- ~* k
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is defined to be $ }( D1 T; e% ?8 S0 H" }
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7 j9 g! @, `3 U3 H is said to be
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2. Something something(or adjective) & J. C3 [( D4 O& ]1 a4 ^& x
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The difference A-B is defined to be the set of all elements of A which are not in B. 0 A. K; H/ D. w" N0 K; Q" D
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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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' F- V8 n) k6 M; p Real numbers which are greater than zero are said to be positive. ; {5 G) z& c0 J
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define
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call
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3. We something to be something. + o! S0 Q1 ~4 n7 c6 H' H! P
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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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9 d! b( L9 }, N( b, X8 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
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is defined as 5 \; A5 r- B( m6 R
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c/ e7 s. w) n7 W0 q$ f$ Y Let…, then…
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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. 7 u6 Q5 c* G" S" Q; G& [
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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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& e: m% }: J, t o' `5 _5 [" h 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 . @4 v' a6 [! b8 R5 W% a& W; D& u$ f
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is defined to be
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If…, then…
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; }0 l3 H+ Q4 i/ k& {) D5 R9 i# |( z 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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If a function f is differentiable at every point of a domain D, then it is said to be analytic in D. n6 u$ c4 W0 i8 u
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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: ' H& q% A; c5 G
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is called % \5 c4 f) y5 M$ s2 }$ Q2 g
is said to be | % g8 C. _( r8 v8 t
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Let 3 D$ N% |/ S. S0 l9 } u2 L0 }2 f: \
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. - {* ]& z* n: w, ~
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