Submitted on: 19 November 1998.
Revised on: 30 November 1998.
Accepted on: 12 December 1998.
SYNTHESE
http://reply.papertrans.cn/3/292/29112/29112-12.png
http://reply.papertrans.cn/3/292/29112/29112-13.png
Submitted on: 16 December 2006.
Revised on: 09 January 2007.
Accepted on: 29 January 2007.
SYNTHESE
http://reply.papertrans.cn/3/292/29112/29112-15.png
http://reply.papertrans.cn/3/292/29112/29112-16.png
http://reply.papertrans.cn/3/292/29112/29112-17.png
http://reply.papertrans.cn/3/292/29112/29112-18.png
Submitted on: 25 November 2003.
Revised on: 12 December 2003.
Accepted on: 19 December 2003.
SYNTHESE
http://reply.papertrans.cn/3/292/29112/29112-20.png