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数学专业英语-(a) How to define a mathematical term?
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1 t3 D& x0 s& A) k' e6 B& [* b 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。
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# J0 q0 g5 Y* x0 L' L" ~2 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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: I7 ]: E) a7 a8 a 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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1 o5 G. q$ C7 I, |8 r6 n2 ] (a)How to define a mathematical term?( ~6 O8 L" V q2 t) B7 t
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is defined as
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is called * \7 N! S2 U3 N8 }
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. p6 K$ L. W+ `9 w1 o1. Something something
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+ D; P0 N/ O1 c" u* @4 S8 P0 W 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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2 ^! `, D/ {, `) _7 U- n+ ]4 p3 n The mapping , ad-bc 0, is called a Mobius transformation. % T7 F/ m: G8 ^5 u3 {) N d" W# r; u
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is defined to be 4 I! v4 {6 U* ~' S
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2. Something something(or adjective) $ e: B2 C" _+ \5 J
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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. : a$ m! M0 O1 D5 G' Y% p( d& u
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* W/ u& o- k: N Real numbers which are greater than zero are said to be positive. : b% q* R4 F/ y
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& ]9 t- h# i: z6 C define : b, B( {% L! C" q2 G8 v( `$ U+ r
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call
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3. We something to be something. 6 x4 g1 H Y$ l' ?: D
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8 _* {( A% a4 b- ?; G8 e$ Z We define the intersection of A and B to be the set of those elements common to both A and B. 9 n- D9 K( L9 w- r
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f8 e6 ?* x B" r2 q8 f We call real numbers that are less than zero (to be) negative numbers. : C) p8 U- m, L' ` Q7 n
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. t* h0 G0 n3 j, y" W c* r/ d5 G 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 - g6 }; U" R- M7 \' Z* k
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4 j1 W, j) \/ q% ^& f6 O; t Let…, then…
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3 E" X& ?" R0 l) N! x 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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9 E0 S. w3 N' v" ]8 R" J) j V Let d(x,y) denote the distance between two points x and y of a set A. Then the number $ A( f. Q# h0 d9 O
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D=
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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:
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is called k4 h8 C( W# S# k7 z2 H
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is defined as
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is defined to be 2 z$ z: `) b/ I2 G, l( E% M
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If…, then…
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! w% a# w1 n1 R& @ If the number of rows of a matrix A equals the number of its columns, then A is called a square matrix. 2 _$ I: U& n0 i
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8 z1 F3 B1 l. s2 `9 O& V8 W, G 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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2 |2 P% H6 P7 N% c6 V 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: , T `- s7 Q* t) F+ j
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is called
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Let
* F9 p! ]) F6 h2 s: f( y+ xSuppose | …. If…then… … 5 f! o' g0 b- D# Y
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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.
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