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\begin{displaymath}
V(x) = \frac{1}{7} x^7+\frac{1}{5} ax^5+\frac{1}{4} bx^4
+ \frac{1}{3} cx^3+\frac{1}{2} dx^2+ex \; ,
\end{displaymath}

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\begin{displaymath}
V(x) = \frac{1}{8} x^8+\frac{1}{6} ax^6+\frac{1}{5} bx^5
+ \frac{1}{4} cx^4+\frac{1}{3} dx^3+\frac{1}{2} ex^2+fx
\end{displaymath}

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¦pªG¤@­Ó¦ì¨ç¼Æ¤§¤¤§t¦³¨â­ÓÅÜ¼Æ x, y¡A¨Ò¦p¦Ò¼{¡G V1(x,y)=x3+y3+ax+by+cxy¡]¦³¤T­Ó±±¨î¦]¤l¡^¡A©Î V2(x,y)=x3-xy2+ax+by+c(x2+y2)¡]¦³¤T­Ó±±¨î¦]¤l¡^¡A©Î V3(x,y)=x2y+y4+ax+by+cx2+dy2¡]¦³¥|­Ó±±¨î¦]¤l¡^¡C¨º»ò§Ú­Ì·Ó¼Ë¥i¥HÂǵۦҼ{¨ä²Ä¤@¦¸°¾¾É¼Æµ¥©ó¹s¡]¨Ò¦p¦b V1 ªº±¡§Î¡A´N¨ú $\frac{\partial V_1}{\partial x} =3x^2+a+cy=0$ ¤Î $\frac{\partial V_1}{\partial y} =3y^2+b+cx=0$¡^¦Ó±o¥X¤@­Ó¼@Åܦ±Åé¡CµM«á¨D¥X¨ä¤Àª[ÂI¶° (bifurcation set)¡C³o¤@Ãþªº°ò¥»¼@Åܼҫ¬¥s°µÂÀÂI(umbilic)¼@Åܼҫ¬¡A¥Ñ©ó¬Û·í½ÆÂø¤Î½g´Tªº­­¨î¡A§Ú­Ì¦b³o¨à¤£¥[¥H°Q½×¡C

¤w¸g¦³«D±`ºë½T¤SÄYÂÔªº¼Æ¾Ç²z½×§â©Ò¦³Âǵ۬Y¤@­Ó¦ì¨ç¼Æ¤§·¥¤p©Ò±o¥Xªº¼@Åܲ{¶H¥[¥H¤ÀÃþ¡A³o¼Ëªº²z½×´N¥s°µ°ò¥»¼@ÅܽסC³o¤è­±³Ì¥X¦Wªº©w²z´N¬O¸³Â§¤º±Ð±Âªº¤ÀÃþ©w²z¡A¨ä¤¤»¡¨ì¦pªG§Ú­Ì¥u¦Ò¼{¥|­Ó±±¨î¦]¤l¡A¨º»òÂǧU©ó¤@­Ó¦ì¨ç¼Æ¤§·¥¤p©Ò¯à±o¨ìªº¤£³sÄò©Êªº¼@Åܲ{¶H¬Ò¤£¥~©ó¤W­±©Ò½sªº¤CºØ°ò¥»¼@Åܼҫ¬(¥|­Ó¦y±Ú¼@ÅÜ¡A¤T­ÓÂÀÂI¼@ÅÜ)¤§¤¤©Ò¥X²{ªº¡C¬°¤FÃÒ©ú¸³±Ð±Â³o¼Ëªº¤ÀÃþ©w²z¡A¦³³\¦hªº¼Æ¾Ç²z½×»P¤u¨ã³Q³Ð³y»P¹B¥Î°_¨Ó¡A¨Ò¦p³eºI©Ê (transversality) ªº²z½×©ÎªÌ´¶¹M©î®i (universal unfolding) ªº²z½×µ¥µ¥¡C¦]¦¹¼@ÅܽשúÅã¦a¤Þµo¤F³\¦h¼Æ¾Ç·s²z½×ªºµo®i¡C¬ö°Ò±Ð±ÂÁ¿¹L³o¼Ëªº¤@­Ó¬G¨Æ:¦b¤@¤E¤»0¦~¥Nªºªì´Á¡A·í¸³±Ð±Â¥¿¦bµo®i¥Lªº¤ÀÃþ²z½×®É¡A¥L«æ»Ý¤@¨Ç¯S§Oªº¤u¨ã¡C­n¬O¬Y¤@¨ÇªF¦è¯à°÷·ÓµÛ¥Lªº²z·Q³QÁ¿¥þ¤F¡A¨º»ò¥Lªº¤ÀÃþ©w²z¤j·§´N¨S°ÝÃD¤F¡C¬°³o¨Æ¥L§ä¤W¤F°¨Äõªv (Malgrange) ±Ð±Â¡A­n°¨±Ð±Â³]ªk·d¥X³o¨ÇªF¦è¨Ó¡C°_ªì°¨±Ð±Â¦³¨Ç¤£Ä@·N¡A¦]¬°°ÝÃD¬Û·í¤£Â²³æ¡A¦ý¬O«á¨Ó¥L²×©ó·d¤F¥X¨Ó¡A¦Ó¸Ñ¨M¤F¤ÀÃþ©w²z¡C«á¨Ó¤j®a´N¤@ª½§â³o¨Ç³Â·ÐªºªF¦èºÙ¬°°¨¤ó¹w³Æ©w²z (Malgrange preparation theorem)¡C¹³³o¼Ë¡A¼@Åܽפ޵o¤S±a°Ê¤F³\¦h¼Æ¾Ç·s²z½×ªºµo®i¡A³o¬O¼@Åܽ׭«¤j°^Äm¤§¤@¡C

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