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： 0 ~4 h( X' S' q1 y1 M% j% X0 a# b) V3 B" g4 j
Formal Sets * e- _8 }; t" Q+ l4 O* l5 `7 WA formal set consists of the subset of elements of some carrier set (structure) on which a certain predicate assumes the value `true'. - E, Y+ `+ C9 A, d4 k) W5 u7 {) s" @
; f' m7 e, {- t5 y" j$ J% nThe only set-theoretic operations that can be performed on formal sets are union, intersection, difference and symmetric difference, and element membership testing. 7 i% r* e- y% N' S5 k! p : L( l+ J' h' {8 Y ^) w1 \' `5 _& ]8 O; v& U, |2 I1 J: y& ?! @/ i% a+ w. a
S := { 1 .. 5}; ! |+ U" V# l! j8 Z> P := PowerSet(S); 4 ^, s7 n. N* L2 W/ R# cP;' i( F1 K# h' g6 y
PFS:=PowerFormalSet(S);# ?7 v. C( {5 _( o9 h
PFS;. q9 T) K/ q- \
F := { 2, 4 }; 1 U+ e/ Y. a1 @. q1 _FF := { 2/3, 4 }; # D3 Z' @6 ]% G& z* Y4 j- q) y. u( P+ K2 X$ i: v3 L7 v2 t U1 }$ P |
F in P; 8 n. Y5 i5 Z! T5 M# tFF in P; ' z! g8 Y5 V# R' f ^ F in PFS;( n) I" T( X7 i3 i( ?) p
FF in PFS; 6 x! G( x& W" V6 p2 s- YSet of subsets of { 1 .. 5 }$ \8 p' g: G: D5 I
Set of formal subsets of { 1 .. 5 } % c% e" |; X; M" \: o5 k' w' a# W! Ltrue 8 ~& t0 l( N, Yfalse' w) ]9 @$ A6 ^# O5 w+ _( {( L
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>> F in PFS; " ~3 N' c+ |) v ^+ ?2 o2 m8 I; ]+ `: i( q4 O1 H
Runtime error in 'in': Bad argument types ' R4 l& N+ h0 o; \( |% ^/ _6 i9 k9 W9 Y* u
/ K! L U+ u! s. ^' j: P>> FF in PFS; y/ x$ Z6 J; m% h$ g
^ ' l' ~ N! m" W: l* hRuntime error in 'in': Bad argument types