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数学专业英语-(a) How to define a mathematical term?; f& `' i( B- @6 M( ~7 G! i
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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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2 {2 o" W5 Y# i E( U& m! v2 Q, J2 R 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。 : [& h! d& [0 E
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3 J) [) c' R/ R1 M 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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; V4 Z5 l: B# b4 W$ R. U3 F. 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)。 % [1 }( A% p" n. C
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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?
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- W- H2 p1 }/ v5 E1 |& o5 g' q is defined as , w/ O" c1 _; u! U1 A
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0 ~9 c1 e! }, Y5 j7 P. {+ y9 z is called 2 q8 J/ a- Y9 ~& _' n6 p& A
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1. Something something ( z5 s( _2 Q) ^6 }( e3 o# [
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" ~$ _' O4 I/ i4 D+ \8 h" e$ H" o# g The union of A and B is defined as the set of those elements which are in A, in B or in both. ( I+ B; K7 W+ s( G1 Z8 H+ z
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2 a! F- @. L+ f! F9 y" Z# } The mapping , ad-bc 0, is called a Mobius transformation. ; n( F* ?" Q* x) |' z9 _7 W
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is said to be ; n3 y+ r( Q, V4 J
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2. Something something(or adjective) % \' h. L0 ^6 N0 e
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The difference A-B is defined to be the set of all elements of A which are not in B. 9 }) z7 i% Z7 @. g/ ]
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7 N- I1 I& k' X4 ?$ P% X A real number that cannot be expressed as the ratio of two integers is said to be an irrational number. $ A6 y( { x( j( Z2 I6 f/ v, O9 @6 B
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" x! e% I1 X4 ^0 ~- S; r3 C Real numbers which are greater than zero are said to be positive.
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define
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# g4 K; C6 w s# n9 w! J* d% m2 X3. We something to be something. ! O2 C1 m9 v* i" E: j+ g6 h
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3 w: {& j( |1 e, R$ O We define the intersection of A and B to be the set of those elements common to both A and B. ) d8 @% o) d/ O& B4 f% @) ^- o
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We call real numbers that are less than zero (to be) negative numbers. ) q, c8 p9 {3 f6 J( l
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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: ; ^ B' P5 i' u3 r7 v
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is called 5 g' ~$ l3 O7 k5 H
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' }. p5 F( T$ P3 A8 q1 }5 p is defined as
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is defined to be
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Let…, then… 6 R R. r2 F( c) H+ u6 e
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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. ' R" i9 k# ?; y9 [ j( d
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Let d(x,y) denote the distance between two points x and y of a set A. Then the number 4 n7 x. ]4 c: b9 e' s- I
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D= 3 _, \0 [! w L
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5 v& Z2 W6 K) h* d7 j) C' c 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 defined to be
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If…, then… ; v2 n( j9 [- {* i9 @
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* D( m# N7 K7 Z7 h% F$ n* L If the number of rows of a matrix A equals the number of its columns, then A is called a square matrix. # I9 a. N" r$ S2 M- `3 J7 _* u$ Q
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0 @$ ]% M4 ?. ^3 ` If a function f is differentiable at every point of a domain D, then it is said to be analytic in D. : }7 A: S& e! H6 ^5 e
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+ M& d6 l- B* D" l$ u2 X 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: . k5 K& H9 R) c$ B) i \, S
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: s I- }" c C+ E, p- Q! L* A! His called % v% L" s" c$ S5 X# L8 W+ |/ E
is said to be |
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Let
b+ F1 r' ^3 q6 M: A- j) ^1 nSuppose | …. If…then… … ; t c2 I: y- o7 ~" m) f
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" [3 {% K. _3 k+ Z. l 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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