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数学专业英语-(a) How to define a mathematical term?/ H: l# g' |) R/ F/ G$ H
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+ E6 l: s$ G/ r7 n4 S6 R 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。 8 _2 \# x+ E: v$ @* I
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- x7 X! q- M- c! }1 |+ | 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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; D8 j5 p5 j6 w$ 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)。
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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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(a)How to define a mathematical term?& R% [5 V/ p' J2 u$ g
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+ N3 [- ~) k; \5 ] is defined as - d8 y0 j1 F# |' i' [ j
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7 D; v7 p3 s: T is called 6 |. Y( x1 h; l
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1. Something something
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4 Q$ t3 b, z) }! T* f+ ~ The union of A and B is defined as the set of those elements which are in A, in B or in both. : y0 x) P# y! q/ k# ^7 _ O" i
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The mapping , ad-bc 0, is called a Mobius transformation. 4 Y+ v+ U- C& W! n& D* Q9 w* I
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is defined to be
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is said to be H8 M% w+ |8 k3 ^8 ~, O
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2. Something something(or adjective)
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! F9 A8 F3 M; {. e" [ 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. 7 o; U4 G8 |& n, m4 D" ^8 ?
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Real numbers which are greater than zero are said to be positive. ) k+ V1 d4 X6 f- m
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define # v6 X* n; a+ e/ F* K: \8 J1 `4 v
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* x% K$ ?- E" b, b8 \3. We something to be something.
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8 J$ s9 M: w& T# b9 j" k7 D% n! v We define the intersection of A and B to be the set of those elements common to both A and B. ' n6 _) S! T6 f. M
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We call real numbers that are less than zero (to be) negative numbers. 9 {! t# K9 s) l/ `4 Y4 [# U0 w
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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: . H- q g3 s1 {& `# i
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is called 4 n; N! k# u: N
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is said to be
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" q8 j- o0 I; t$ }4 J% c- O is defined as
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is defined to be 1 F# O# h' Q* B+ O/ a, ]
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Let…, then… 0 I% O1 L/ _ v% a% O H
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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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Let d(x,y) denote the distance between two points x and y of a set A. Then the number
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D=
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is called the diameter of A. # D, A/ ?% h- M7 E" Z
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5 Q! B# S3 ~' r B7 M( [ 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
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If…, then… : ^; G$ }2 G- N" D8 `
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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.
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6 Q4 R6 s# {- N 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: 7 X4 R! C% K6 I/ n
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is called
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Let
( w: F$ v7 ]6 R/ tSuppose | …. If…then… … : j! B( }3 y, E0 S
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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. , I5 J _( D( H M8 Y$ d
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