Submitted on: 14 November 1999.
Revised on: 14 January 2000.
Accepted on: 21 February 2000.
___________________HOUSTON JOURNAL OF MATHEMATICS
http://reply.papertrans.cn/2/116/11528/11528-12.png
Submitted on: 06 November 1998.
Revised on: 18 January 1999.
Accepted on: 04 February 1999.
___________________HOUSTON JOURNAL OF MATHEMATICS
Submitted on: 23 December 2022.
Revised on: 21 April 2023.
Accepted on: 17 June 2023.
___________________HOUSTON JOURNAL OF MATHEMATICS
Submitted on: 27 March 2015.
Revised on: 22 June 2015.
Accepted on: 09 August 2015.
___________________HOUSTON JOURNAL OF MATHEMATICS
Submitted on: 20 August 2019.
Revised on: 09 October 2019.
Accepted on: 20 October 2019.
___________________HOUSTON JOURNAL OF MATHEMATICS
http://reply.papertrans.cn/2/116/11528/11528-17.png
http://reply.papertrans.cn/2/116/11528/11528-18.png
Submitted on: 13 October 2004.
Revised on: 05 January 2005.
Accepted on: 03 February 2005.
___________________HOUSTON JOURNAL OF MATHEMATICS
http://reply.papertrans.cn/2/116/11528/11528-20.png