`red'
-----

red(RAT)
     :: RAT $B$rLsJ,$7$?$b$N(B.

RETURN
     $BM-M}<0(B

RAT
     $BM-M}<0(B

   * Asir $B$OM-M}?t$NLsJ,$r>o$K<+F0E*$K9T$&(B.  $B$7$+$7(B,
     $BM-M}<0$K$D$$$F$ODLJ,$O9T$&$,(B,
     $BLsJ,$O%f!<%6!<$,;XDj$7$J$$8B$j9T$o$J$$(B.  $B$3$NLsJ,$r9T$&%3%^%s%I$,(B
     red $B$G$"$k(B.

   * EZGCD $B$K$h$j(B RAT $B$NJ,;R(B, $BJ,Jl$rLsJ,$9$k(B.

   * $B=PNO$5$l$kM-M}<0$NJ,Jl$NB?9`<0$O(B, $B3F78?t$N(B GCD $B$,(B 1 $B$N(B
     $B@0?t78?tB?9`<0$G$"$k(B.
     $BJ,;R$K$D$$$F$O@0?t78?tB?9`<0$H$J$k$H$O8B$i$J$$(B.

   * GCD $B$OBgJQ=E$$1i;;$J$N$G(B,
     $BB>$NJ}K!$G=|$1$k6&DL0x;R$O2DG=$J8B$j=|$/$N$,(B $BK>$^$7$$(B. $B$^$?(B, $BJ,Jl(B,
     $BJ,;R$,Bg$-$/$J$C$F$+$i$N$3$NH!?t$N8F$S=P$7$O(B,
     $BHs>o$K;~4V$,3]$+$k>l9g$,B?$$(B. $BM-M}<01i;;$r9T$&>l9g$O(B, $B$"$kDxEY(B
     $BIQHK$K(B, $BLsJ,$r9T$&I,MW$,$"$k(B.

     [0] (x^3-1)/(x-1);
     (x^3-1)/(x-1)
     [1] red((x^3-1)/(x-1));
     x^2+x+1
     [2] red((x^3+y^3+z^3-3*x*y*z)/(x+y+z));
     x^2+(-y-z)*x+y^2-z*y+z^2
     [3] red((3*x*y)/(12*x^2+21*y^3*x));
     (y)/(4*x+7*y^3)
     [4] red((3/4*x^2+5/6*x)/(2*y*x+4/3*x));
     (9/8*x+5/4)/(3*y+2)

$B;2>H(B
     *Note `nm dn': nm dn, *Note `gcd gcdz': gcd gcdz, *Note `ptozp':
     ptozp.

