`deg', `mindeg'
---------------

deg(POLY,VAR)
     :: POLY , ѿ VAR ˴ؤǹ⼡.
mindeg(POLY,VAR)
     :: POLY , ѿ VAR ˴ؤ㼡.

RETURN	
     
POLY
     ¿༰
VAR
     긵

   * Ϳ줿¿༰ѿ VAR ˴ؤǹ⼡, 㼡Ϥ.
   * ѿ VAR ά뤳ȤϽʤ.
   * VAR ѿǤʤ, VAR ѿξӤƸΨ.

     [0] deg((x+y+z)^10,x);
     10
     [1] deg((x+y+z)^10,w);
     0
     [75] mindeg(x^2+3*x*y,x);
     1

