[1] Department of Mathematics,
[2] The University of Pennsylvania,undefined
[3] Philadelphia,undefined
[4] PA 19104-6395,undefined
[5] USA.¶ E-mail: borodine@math.upenn.edu,undefined
[6] Dobrushin Mathematics Laboratory,undefined
[7] Institute for Problems of Information Transmission,undefined
[8] ¶Bolshoy Karetny 19,undefined
[9] 101447 Moscow GSP-4,undefined
[10] Russia. E-mail: olsh@iitp.ru; olsh@online.ru,undefined