数学专业英语-(a) How to define a mathematical term?
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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。 + m4 u& X0 R! C1 ^3 `# O- x- D
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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。 0 y' Z% C5 E# F( z, @ p) {( t
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( {$ E* i# X& v( S% C _* l 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)。 ! ?/ r! R* w8 q8 Q
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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。 5 A* F: P0 y$ f& q& ~' i; U
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& u- g$ \+ R \: E. b (a)How to define a mathematical term?
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is defined as # b4 P2 y0 N6 L& N' U' F
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is called 7 s" J. r: g1 G) D7 H
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1. 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.
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The mapping , ad-bc 0, is called a Mobius transformation. U) R" Z0 }2 ~+ @* I# Q
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is defined to be ' n2 a a" n! Q6 m1 s4 z% g
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& y* A$ F( O6 S8 x \6 a is said to be
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2. Something something(or adjective) , G; V+ u# z! L
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6 M1 }1 R' c0 C& w. m 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.
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Real numbers which are greater than zero are said to be positive. $ C, v: R# O" ~8 P
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define * }6 u# |2 T$ x7 ?2 u x' u0 v- f
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# J \" |3 G8 c+ G. m3. We something to be something.
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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. ; H6 Z" Q$ E1 T7 h
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We call real numbers that are less than zero (to be) negative numbers. 8 }, _! H* w5 {, m% d( X
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! w, U% \4 P7 x1 R5 Y- V 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 G/ y, _; X% |3 K {# e
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is defined to be
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Let…, then… 7 ?) ^3 y. v9 I$ Z# j5 \
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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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/ w2 S+ G6 O$ F( | k3 ? Let d(x,y) denote the distance between two points x and y of a set A. Then the number
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; s, N) o) `5 Z5 Q0 c is called the diameter of A.
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# L/ |/ _, l8 }+ f4 o" x+ _ 5.如果被定义术语,需要满足某些条件,则可用如下形式: 8 L6 t4 u5 ?0 c. Y9 d, [/ Q
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8 ~- H9 |* G, q! x( t2 k is called
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is defined as O4 e7 E: R0 _2 S( H+ u
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is defined to be
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|
3 [- O* n; v7 G) p) }, r If…, then…
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# S: } S4 B: T 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. n( [' l& h$ F$ a
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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: 0 N5 y7 f0 D* T3 @6 e3 {. A
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is called 6 a' t4 P) q/ P& d
is said to be | ' Y" X m9 M% ?" ^* t
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Let ( \2 q( t/ @( f. i, H" g( b. e1 ]
Suppose | …. If…then… … : K; ~# Q j0 d2 f5 _3 C% C
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( U5 W1 F7 D9 S8 a 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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