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： * p# f. o2 B; w 3 \) M, R& M' O- [, n/ W3 AFormal Sets " X) r2 C# k0 r1 ~% m$ _& s' ~A formal set consists of the subset of elements of some carrier set (structure) on which a certain predicate assumes the value `true'. ; C8 W( f6 W5 P6 |) D* Y. ~0 P7 ~
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The only set-theoretic operations that can be performed on formal sets are union, intersection, difference and symmetric difference, and element membership testing. , p( D; }, [- U$ {, }* h: m; l' d: Y7 _0 o8 o/ G( a: I' d! n
* d: h( H6 L/ N * U j, K) o# ^$ MS := { 1 .. 5}; / D' G" q$ T3 ~3 \' x6 U1 w> P := PowerSet(S); 0 F* |* X* f P ~' e$ c9 _- P) iP;- C% L* L! t3 H" c# ~* B/ ^
PFS:=PowerFormalSet(S); ! u0 `9 \! } [PFS; i8 F/ N7 W- U7 D7 S& H- JF := { 2, 4 }; 4 ]& H3 K* y( F+ @0 [$ J( aFF := { 2/3, 4 }; 9 m4 N! o- P( {2 k* X$ |! s6 J2 h4 c 0 B/ T, v. }) i F in P; $ c; B- b2 `; l9 U& `FF in P;1 G5 q1 K2 {& V) U( I; @3 k
F in PFS;$ v7 o2 G2 u! U% l
FF in PFS; % L2 j! C4 `" x% e$ GSet of subsets of { 1 .. 5 }2 t& |* B0 g- V' a' N& t n
Set of formal subsets of { 1 .. 5 } 2 G- \9 v5 r) \, J8 Utrue ) \, P+ O/ P( _false( s! M' L, r! A" Z: `
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Runtime error in 'in': Bad argument types+ P0 \) a0 I! j
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9 L! |" E! z& e8 b- M>> FF in PFS;% a$ b# X& W( H8 z8 q
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Runtime error in 'in': Bad argument types