RE: the most common structure

I dont' have the answer, but I will ask a clarifying question that may help
 If you take the phrase "most common structure" literally, it means the
 (sub)structure which is present in the greatest number of compounds in the
 set.  This would end up being individual atoms like C or H, if we don't make
 any restrictions on what is a structure.  But if there is a restriction, for
 example that a "structure" must consist of at least 5 atoms, then this
 be a meaningful question with a nontrivial answer.
 However, the above interpretation relies on a fine point of English usage,
 and I would not be surprised if the intended request is for the LARGEST
 common structure, that is the largest substructure which is present in ALL
 of the compounds of the set.
 Note that "common" can mean either "occurring frequently" as
 in the first
 interpretation, or "occurring in all" as in the second.
 I didn't mean to turn this into an English lesson, but I hope this ensures
 that the right question is answered.
 --David Shobe
 S?-Chemie Inc.
 phone (502) 634-7409
 fax     (502) 634-7724
 email  dshobe -AatT-
 Don't bother flaming me: I'm behind a firewall.
 -----Original Message-----
 From: chem_liqiang -AatT- [mailto:chem_liqiang -AatT-]
 Sent: Monday, July 08, 2002 10:38 AM
 To: chemistry -AatT-
 Subject: CCL:the most common structure
     Good morning.
 	Who can tell me how to pick up the most common structure from a set
 of compounds, and save it into a structure file? Could you indicate to me
 further softwares able to perform the same task? I have SYBYL software, but
 no DISTILL module.
       Thank you very much!
 Li Qiang
 Shanghai Institute of Organic Chemistry
 Chinese Academy of Sciences
 No.354 Road FengLin
 ShangHai, 200032, China
 Phone: 08621-64163300-2735
 Fax: 08621-64166128