????$B&N(B??

???	?????
???	?$(D)P(B ?$(D*4*B$B"y$(D"B"p*)*A*4*X(B ??$B!k$(D+@"B"p(B?$(D*A(B?$B"L(B ?$(D*4(B
????	?$(D)C(B?$(D*4(B?$(D+2*!+d"p(B?$(D"p+1"p*B$B!-$(D*.*2*#*B*B$B!k$(D+2"p*2$B!-$(D*.*2*#**)A"p*B(B?$(D)C*4+Q**+4(B?? $(D"B(B?$B!k$(D*$*#+4*.),(B?$(D*4*B*B$B!k$(D+2"p*B"D+#*#+4"B(B?
??????	$(D"D"n(B?$(D),(B??$(D*4+Q(B
Series	PRMU2002-217
???	2003?2??

????????