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： t5 h: a% M3 Z( e ! N$ c# [/ ^0 _Formal Sets0 a: d0 i9 t2 K; Z& p' }7 ^. m8 Z
A formal set consists of the subset of elements of some carrier set (structure) on which a certain predicate assumes the value `true'. $ t" b W* t- O- ]
+ m9 A# f1 ~) A6 q+ g U, y! bThe only set-theoretic operations that can be performed on formal sets are union, intersection, difference and symmetric difference, and element membership testing. 1 M0 p: J8 `. X5 o; k9 P
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/ R. p: e* E/ E* ~6 w, P* w9 o / a+ Z, }5 L! C8 ]# oS := { 1 .. 5}; ! ^. v, N, \3 `/ H; ~> P := PowerSet(S);) \5 H% ~! Q% ^5 a* K& r
P; & k; U, S. S# Z' J: H) p5 Z; O" m4 iPFS:=PowerFormalSet(S); 1 u; [2 |" G( k- y, y, x' W$ dPFS;* Y! N ?) P6 l& }! U
F := { 2, 4 }; ( u+ H* l' X# qFF := { 2/3, 4 }; " v( m$ m3 D+ q6 {+ @! n5 G! R* G/ |! E
F in P;$ T8 C1 O0 ` t; O1 S
FF in P;! F9 c( b7 W( m
F in PFS;0 V9 h; z7 ^ K6 F1 {! E
FF in PFS;7 a, W( \2 U& Y0 a0 @
Set of subsets of { 1 .. 5 }9 A) ~0 P0 C S0 z
Set of formal subsets of { 1 .. 5 }8 [ A! c( J; a0 k/ v: [- g
true8 X0 {9 g5 e1 h# ^" x8 m& T' N0 ]1 [
false+ x8 f. A6 O/ h# n& C" B1 T G
( V5 w5 P4 H, e% d9 ^/ B5 ?>> F in PFS; * D0 A9 w2 s8 @7 y& Y K4 @6 m ^6 A; k+ k" ~ g* c, {6 Z" S
Runtime error in 'in': Bad argument types * v4 I' j- z( z0 ]" s G7 K. b4 \: M8 n4 K1 r" G
- j+ i' U: @& g) e/ P/ `9 s& {1 G! x>> FF in PFS; / C. Q$ {0 V" P2 i ^4 G* w' H9 r# @) M o3 j
Runtime error in 'in': Bad argument types