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数学专业英语-(a) How to define a mathematical term?9 h, Z* t9 P9 ~' r' ^
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: D, `( k( \# n/ _7 [+ s+ C 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。 ) t' u0 p w. g7 g1 T6 [% y; R1 l% U) G
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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。 * y' K( M' `" {) p t
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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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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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/ g# Y+ a+ i3 S8 @6 c 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。 ; K9 ]5 p; L( H% T) I# u% u
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; e* l8 s6 g$ S3 g* L+ X9 J4 U (a)How to define a mathematical term?
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is defined as
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& S$ A e/ x# z( @! [ is called
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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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( m; ?( L7 t( h' p) F The mapping , ad-bc 0, is called a Mobius transformation. % @( [9 q7 ~$ l! n& M8 d
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is said to be ) W+ {7 {$ n% x" k2 q3 R. P% v/ g4 `
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5 U) j, g* G! T ^# O2. Something something(or adjective) # V6 y/ Y0 \2 D0 u8 S4 V, b
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+ f$ X2 I8 Y8 I" ?+ u( l The difference A-B is defined to be the set of all elements of A which are not in B. 1 i& @# c5 X0 n/ g9 L: o- m3 @2 m
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A real number that cannot be expressed as the ratio of two integers is said to be an irrational number. & r# R, f* ]2 j2 O B3 X" L
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4 [3 _1 L! h" f2 [9 g7 t& A Real numbers which are greater than zero are said to be positive. 4 B( Q+ ^5 n0 V7 r
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& q. D) t1 ]9 H define ! B: K; [. J% @" o# ?6 T
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$ N# h( m, U* Y' Q8 [& `' D3 a0 D3. We something to be something. 9 W* I `1 l1 ~- d0 ?
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2 h! ]9 t, O: ~/ C9 E We define the intersection of A and B to be the set of those elements common to both A and B. $ N# \1 b. J* ~. K q6 Q8 }
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We call real numbers that are less than zero (to be) negative numbers.
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+ u. U b% I0 _( E0 q2 K 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
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is said to be 3 g2 ]6 x& w) ?7 J
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is defined as ' z) `$ Q9 y- ?' J
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is defined to be
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Let…, then… . Z/ N/ p8 D: w& ^9 r) b
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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. ; i: x" A1 j# ^) f
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. j3 `8 i1 L0 d. v0 v, X8 z+ l Let d(x,y) denote the distance between two points x and y of a set A. Then the number 1 e8 c" h7 @ J Y Z4 }) W
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D=
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; S7 X4 a4 k; q/ t7 n5 G) [ 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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9 {2 Z0 T2 W& R5 q9 H is called
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is said to be
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is defined as - F6 g1 D1 e# K* a0 M' t
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If…, then…
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7 R6 O D& A. G If the number of rows of a matrix A equals the number of its columns, then A is called a square matrix. * f- ~4 h+ E$ _9 J. U# g) v
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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.
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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: * z0 w5 ~5 X* d. {# m1 V0 j) ~
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is called 4 n3 G' ~- P" ~8 s" `: R
is said to be |
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Let
& M" c- l1 e! ]: u) o% R1 X6 V5 ^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. ! ?* { u' a' `
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