Re: generating subsets
- To: mathgroup at smc.vnet.net
- Subject: [mg21602] Re: generating subsets
- From: "Allan Hayes" <hay at haystack.demon.co.uk>
- Date: Sun, 16 Jan 2000 22:43:49 -0500 (EST)
- References: <85s189$aj3@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Michael, Looking up Subsets in the Help Browser leads to << DiscreteMath`Combinatorica` Subsets[Range[9]]; // Timing {0.06 Second, Null} Allan --------------------- Allan Hayes Mathematica Training and Consulting Leicester UK www.haystack.demon.co.uk hay at haystack.demon.co.uk Voice: +44 (0)116 271 4198 Fax: +44 (0)870 164 0565 "Michael Gass" <mgass at bach.math.csbsju.edu> wrote in message news:85s189$aj3 at smc.vnet.net... > > I need an _efficient_ procedure for generating all the subsets > of a given set. The procedure should produce output as follows: > > subSets[{a,b,c}] > produces > {{}, {a}, {b}, {c}, {a,b}, {a,c}, {b,c}, {a,b,c}} > > I have written a recursive procedure to do this, but > it takes quite a while to generate, say, the 512 subsets > of a 9 element set and I need to work with somewhat larger > sets. > > Thanks > > -- > Michael Gass Department of Mathematics > phone: 320 363-3090 St. John's University > email: mgass at csbsju.edu Collegeville, MN 56321-3000 > > > > >