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数学专业英语-(a) How to define a mathematical term?! I( x) D | `5 \/ M
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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。 " U1 k1 L( C7 }5 U1 Y9 Z0 Z6 w; {5 K: a
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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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7 K" a1 ~' O8 J3 p! O( b# I 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)。 ! j5 _8 Y! T, m5 g; B- Y% _
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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。
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% J1 l# K5 Q4 \5 L9 g (a)How to define a mathematical term?
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is defined as
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1. Something something 4 A) \8 k& \1 ?; D
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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. 2 ^! x1 S; R! D4 b& j
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The mapping , ad-bc 0, is called a Mobius transformation.
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is defined to be 4 ?6 a8 `+ a% N, A- a
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is said to be ' p9 z: c' z0 G: S t
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. G% s& E$ m7 @; x4 o, D2. Something something(or adjective)
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0 f/ ?- ~* D D$ p0 F2 j 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. ; W: b) f+ G8 U0 M; d
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Real numbers which are greater than zero are said to be positive.
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: a# n( u$ j' @3 `1 F define
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2 \- i, `0 i; x8 w3. We something to be something. 5 @' r& u- t0 s* u. ] R
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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. 2 o" x$ P3 h$ }1 A9 b% ` d! R
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We call real numbers that are less than zero (to be) negative numbers. 2 V" b4 `8 L8 M* k! `
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3 T& W( K) t/ H4 a+ 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: + D) B0 B; I3 G7 m. B9 K8 {* q9 i
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is said to be $ h% W7 l$ N$ u8 j( L
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# @! T2 d8 \$ \! s6 l is defined as 7 E; P7 }) M! w' c
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# E9 h# B1 m6 p6 r 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. " P; l2 f- ?$ A3 ^
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Let d(x,y) denote the distance between two points x and y of a set A. Then the number 0 Q( K) Q! S9 i% }
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& O; B# i0 N6 D5 s 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 ' w: R2 q6 f# g; `
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is defined as
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+ I& p8 M, a3 A* H6 K If…, then…
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5 I2 \$ M T" L5 D0 }( t, g If the number of rows of a matrix A equals the number of its columns, then A is called a square matrix. # r! _& w* z5 J2 p
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/ I! c6 B) _2 ` If a function f is differentiable at every point of a domain D, then it is said to be analytic in D. + M' k; i( v& I% X! {! 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: 9 _- x4 ?1 F! D- X4 H( G& d
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Let # v O: N% \( Y
Suppose | …. If…then… … ! l4 I7 w( C: I- ?5 v9 c/ M
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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. # G6 V3 O: o6 c5 A Y) G
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