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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。
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+ |1 C3 T+ {1 D5 K% P3 h 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。 . z. `0 [# d* N; m
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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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( ?* T8 T/ _' k' i$ J 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?
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( r5 ]% M8 ^9 ~5 S. } is defined as " m# I2 \4 o6 G, F- z' ?4 I
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1. Something something
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; o8 q7 e3 ~# b; b9 ]/ c: S 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 b$ W( _0 l8 h7 C5 g The mapping , ad-bc 0, is called a Mobius transformation.
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is defined to be ! Q6 c* p! v7 ]: A# J
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# s- _' p0 A. J) c. `$ H4 _2 N/ S is said to be - k+ Z% R, l# F) W# d5 R
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2. Something something(or adjective) ( ~, p+ h: q% m+ k
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D1 Z9 P0 r3 \' F/ A The difference A-B is defined to be the set of all elements of A which are not in B. + `9 {# L8 h" D- v0 c5 K7 d; f0 s9 S- r
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A real number that cannot be expressed as the ratio of two integers is said to be an irrational number. 5 I( m1 u. V. f- N
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4 \0 t% |. E; @0 a/ V; K Real numbers which are greater than zero are said to be positive. 9 y$ _% M( l0 z* o
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) `& U) G. g+ `. H+ W7 [% H define - I$ \4 X! {. }/ T7 g# t
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1 ~6 P: x1 |2 e. }, z3. We something to be something.
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( v5 P+ Y6 M1 B We define the intersection of A and B to be the set of those elements common to both A and B. 7 @5 A/ R9 a! @# P
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We call real numbers that are less than zero (to be) negative numbers.
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% K4 s6 \; J2 d. i4 u' o1 s 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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F2 W ]" n1 M( u; F is called 1 f* k( b7 D v* t# H. @% L) B
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is said to be 8 Q4 [0 G- G9 r \
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- W( H6 e- P; z/ Q/ ? is defined as
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" u8 q( g- n! J' E/ d Let…, then…
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0 ]" x& \% F& p6 R# ?- v0 b 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. $ z: j! J2 t. o- N7 ?
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: }- A' S1 B: a1 S: D6 G6 V/ ]/ [ Let d(x,y) denote the distance between two points x and y of a set A. Then the number
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is called the diameter of A.
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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: ' X" F5 K0 R; P4 X4 ^/ C; H
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6 t+ [* T0 p% z* B/ q( s is called
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is defined as 3 e- y- Q/ o5 Q
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If…, then… 9 i- v0 m& h+ m6 ? L0 R
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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. ) {8 F2 ] W. @4 h5 ]' i s
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/ z2 H" k+ Q9 |2 }$ y 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:
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is called " A' j7 z" c8 y, u. A; Z* w
is said to be |
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Let ! V6 w, m( v0 D$ @- `) r* v1 }
Suppose | …. If…then… …
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6 M; S$ M$ Q6 _4 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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