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数学专业英语-(a) How to define a mathematical term?! u' C. I. C' X+ a5 b# Z; w
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; e) X+ \2 x& O$ s. h1 J 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。 4 v, Y$ h$ P I2 o1 G/ y# M- f
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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。 4 i; `! L( h6 r( d: d
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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。 8 G6 E9 E, J; x; u: i2 z1 v0 B
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9 B( r% ^& i# a3 W3 M7 K" f, h4 a. y 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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# f" l9 h1 a* X& ?) n2 P* P# n 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。 5 Y1 }7 |5 F' J4 X: o- K
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(a)How to define a mathematical term?: u, U3 U" h8 z9 t
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/ i9 `/ t, _% ?3 Z is defined as
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8 u3 I2 G9 {8 X) q _ is called
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7 t6 A5 v- U4 o1 P( Y, q* Y3 V/ E% [1. Something something 7 p$ r# w; R7 l. X! ?& u9 [8 V
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6 I# Y: Z3 Z+ x4 x4 U0 r 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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The mapping , ad-bc 0, is called a Mobius transformation.
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2. Something something(or adjective)
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The difference A-B is defined to be the set of all elements of A which are not in B. # W$ x6 j q* q3 o' _
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A real number that cannot be expressed as the ratio of two integers is said to be an irrational number. ( Z9 L, b6 q7 I: f
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Real numbers which are greater than zero are said to be positive.
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6 r' ]0 t" M2 ^' E; g! a define $ P$ m& _0 g& _9 m3 ~% f" O4 Q
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3. We something to be something. & b/ H6 C! B7 n: _; U4 t* {
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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.
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! D& _6 z- C# I. P7 C8 p We call real numbers that are less than zero (to be) negative numbers. 5 g$ k0 O( s6 }8 Y9 A' r
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/ M5 H! q$ k& W3 P7 `4 T 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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. [* `- b' f, ~9 w) F- X3 {! N0 A" k is called 2 X# g: B0 S+ m, F
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is said to be ! F5 n1 k, o/ a
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* {1 ?8 }! i( C" I is defined as ) ]5 \& B* m4 I0 }5 A
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is defined to be . {# T, I" s9 ?5 d6 x: {8 T& K
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Let…, then… 2 n1 O3 q$ G j0 W% h# O# h; C
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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. - d0 X( I2 I6 o. V6 k2 Z
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) U0 a0 K2 j9 R& |2 b. c7 r' |7 ?( v( \ Let d(x,y) denote the distance between two points x and y of a set A. Then the number 4 x: h* N, e6 P6 n6 G+ w+ Y0 P
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( k" y9 v9 _- \1 X& ^6 U7 M* ~" q is called the diameter of A.
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$ i+ S0 O9 C+ l [$ b 5.如果被定义术语,需要满足某些条件,则可用如下形式: * F- T. U3 f$ o! U/ |- G
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/ r6 B- h8 j; n! k( s is called
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is said to be
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0 T0 E' x- n% Q' F5 r( ? If…, then…
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0 a8 M/ q0 X/ q& b# w" V If the number of rows of a matrix A equals the number of its columns, then A is called a square matrix. ) `* `; Z! [1 d2 z
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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. " p" W/ B8 O$ k" t/ d
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& a- c. s- U1 v+ S! i) i 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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1 V! L) ?' N. qis called
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Suppose | …. If…then… … + k' [$ k3 ?' l& J% S+ t* `7 `- M
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0 }% j B3 ~7 I- o. X 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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