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数学专业英语-(a) How to define a mathematical term?# c5 r, e& ]1 I0 I; P- e" F
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/ U8 c( t- { @+ t( B! q 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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* S" V' s' R" s2 N) P+ P 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, p/ P8 M( l; a
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, W1 I: B3 [$ C 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。 ) \1 a! B! Q0 z
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& C% ^/ X6 R) b1 y: H: B8 \' { 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)。 $ V( E* u6 O5 h8 i% q6 |
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3 W2 h7 U6 M! J' I5 g* v+ b 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。 ! U) [0 J* X% X9 x6 W) j
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# i3 }. z j9 D0 I/ Q) ]; h1 p (a)How to define a mathematical term?1 I5 H) o5 L' G
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, p+ @. v: Z+ v7 A* l) ]; C( N2 l, h is defined as
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is called , Q8 _" O0 o4 b) z3 E, H4 C5 Q) m
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1. Something something
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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.
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The mapping , ad-bc 0, is called a Mobius transformation.
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; j7 |( v3 w; Y" j2 \ is defined to be
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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. ; h. q5 }9 e' m3 V, ]- `- E
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A real number that cannot be expressed as the ratio of two integers is said to be an irrational number. 4 X" N$ _4 D0 s' ^2 {, ^3 |3 E; B
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! I0 q& _; `8 X) I' j2 v Real numbers which are greater than zero are said to be positive. $ L/ y' u, A5 W7 S7 b+ {- Y6 \/ o
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; h, _* x! I% N4 ^8 | define
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! y( C9 M- A, {* B; X! k3. We something to be something.
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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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, [/ q/ O+ b' ?9 \* c- l, C$ x We call real numbers that are less than zero (to be) negative numbers. % @" |1 a4 k, c. N, I4 O
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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: 0 R& _: ^) c6 W" ?# T; K
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is called
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is said to be 4 F: Y3 X7 N& i8 T# R5 ?$ v, @
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is defined as 7 t9 b! S( m7 V/ J7 N: N
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is defined to be ! _9 I0 K: Y5 ^. N. s9 S2 e8 c8 g
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Let…, then…
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; a& i$ E; x( a, K 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. * J/ E0 u" t9 C4 T+ a6 V. z
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Let d(x,y) denote the distance between two points x and y of a set A. Then the number & T* C H, H' V; }
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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: ! X7 g, [* g, r0 ~# l% |
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is called * g0 F: G2 ?* v" U3 r
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is said to be
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is defined to be
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If…, then…
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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. ) F, v, E1 B& q" N
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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. 7 T/ R' m- X6 ? E( ]- ?* Y
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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: ! e/ V. |$ F. k, H ]/ m- z
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Suppose | …. If…then… … + l* P# A6 o( I5 J- V6 X9 q# Z
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! G, b y* m" f( r7 W1 _ 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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