标题: 什麽是形式集合Formal Sets/PowerFormalSet？ [打印本页] 作者: lilianjie 时间: 2011-12-30 12:18 标题: 什麽是形式集合Formal Sets/PowerFormalSet？ 哪位能给理解下： ! q- i; R+ c; S7 y( Z- l) q% X , U% _% ~+ I( W3 U& R& w( Y& w0 NFormal Sets . |* I. L* G$ x' s( m, |/ {; XA formal set consists of the subset of elements of some carrier set (structure) on which a certain predicate assumes the value `true'. 9 C/ y3 r2 a4 `+ |5 u. K
0 p( H- o1 O% F6 X4 g+ J- i4 hThe only set-theoretic operations that can be performed on formal sets are union, intersection, difference and symmetric difference, and element membership testing. 5 ~4 q1 h8 t2 ?5 b
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0 U% D: |3 U" u& I) E! ^8 K) eS := { 1 .. 5};) p/ T [3 ^" f/ p5 v5 I' _
> P := PowerSet(S);% e) _+ n2 |' I5 ], {9 x
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PFS:=PowerFormalSet(S); ! b$ x+ |, X, ?% Y/ MPFS; " F: I, J @1 J2 kF := { 2, 4 };9 Q$ Z- B6 f# W, h/ z& P% ?1 }
FF := { 2/3, 4 }; , P# H! H- K8 V! Z( d2 V/ O5 V( m6 f+ ?, F3 d! Q" L
F in P;4 d% r: u$ R9 W3 ?, N4 s
FF in P; ; N# k+ k+ k8 c F in PFS; * K. c9 {/ A! D) RFF in PFS;. Z, T7 T5 s0 f+ A, u
Set of subsets of { 1 .. 5 }5 Z+ }2 P! O, z
Set of formal subsets of { 1 .. 5 }# q0 e2 L% l1 }) x" r- y9 Z
true . V4 z% z. x# N- A9 kfalse 0 L0 h8 [ _$ O. E9 l 7 \* w* a4 C0 Z: M( F( r0 ^0 _>> F in PFS;1 l8 F' [; i9 z! h3 M
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Runtime error in 'in': Bad argument types) _/ G& F2 K' D8 S5 f: c" Q0 ~' b
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>> FF in PFS;5 ?) Q# x& F& d2 \
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Runtime error in 'in': Bad argument types