`defpoly_mod2'
--------------

defpoly_mod2(D)
     :: GF(2) $B>e4{Ls$J0lJQ?tB?9`<0$N@8@.(B

RETURN
     $BB?9`<0(B

D
     $B@5@0?t(B

   * `fff' $B$GDj5A$5$l$F$$$k(B.

   * $BM?$($i$l$?<!?t(B D $B$KBP$7(B, GF(2) $B>e(B D $B<!$N4{LsB?9`<0$rJV$9(B.

   * $B$b$7(B $B4{Ls(B 3 $B9`<0$,B8:_$9$l$P(B, $BBh(B 2 $B9`$N<!?t$,$b$C$H$b>.$5$$(B 3
     $B9`<0(B, $B$b$7(B $B4{Ls(B 3 $B9`<0$,B8:_$7$J$1$l$P(B, $B4{Ls(B 5 $B9`<0$NCf$G(B, $BBh(B 2
     $B9`$N<!?t$,$b$C$H$b>.$5$/(B, $B$=$NCf$GBh(B 3 $B9`$N<!?t$,$b$C$H$b>.$5$/(B,
     $B$=$NCf$GBh(B 4 $B9`$N<!?t$,$b$C$H$b(B $B>.$5$$$b$N$rJV$9(B.


$B;2>H(B
     *Note `setmod_ff': setmod_ff

