[Ì¿Âê6(¤½¤Î£±)¤Î¾ÚÌÀ½ª¤ï¤ê]
¤â¤¦¾¯¤·,¥Ö¡¼¥ëÂå¿ô¤Î½éÅùŪ¤ÊÀ¼Á¤ò¸«¤Æ¤ß¤Þ¤·¤ç¤¦.
(Ì¿Âê6(¤½¤Î2)½ª¤ï¤ê)
¾¯¤·,¥¦¥©¡¼¥ß¥ó¥°¥¢¥Ã¥×¤ò¤·¤Þ¤·¤ç¤¦.
¤µ¤Æ,¥Ö¡¼¥ëÂå¿ô¤Ï«ÏÀ(lattice theory)¤ÎÊý¤«¤éÆÃħÉÕ¤±¤Ç¤¤Þ¤¹¡£
¤Ä¤Þ¤ê,¥Ö¡¼¥ëÂå¿ô¤ÏÁêÊäŪ¤ÊʬÇÛ«¤È¤·¤ÆÄêµÁ¤¹¤ë¤³¤È¤¬¤Ç¤¤Þ¤¹¡£
¤½¤ì¤Ë¤Ä¤¤¤Æ¾¯¤·¿¨¤ì¤Æ¤ª¤¤Þ¤·¤ç¤¦.¾¯¤·Ä¹¤¤½àÈ÷¤¬É¬ÍפǤ¹¡£
¤³¤ÎÀá¤Ï¤½¤Î½àÈ÷¤Ç½ª¤ï¤Ã¤Æ¤·¤Þ¤¤¤Þ¤¹¡£
¼¡Àá¤Ç,
¥Ö¡¼¥ëÂå¿ô¤òÁêÊäŪ¤ÊʬÇÛ«¤È¤·¤ÆÄêµÁ¤·¤Þ¤·¤ç¤¦.
¤Þ¤º,«¤òÄêµÁ¤·¤¿¤¤¤Î¤Ç¤¹¤¬,¤½¤Î¤¿¤á¤ËȾ½ç½ø¤Î³µÇ°¤¬É¬ÍפǤ¹¡£
(½ç½ø¤Ë´Ø¤·¤Æ,ÄêµÁ¤¬Ê¬»¶¤¹¤ë¤È·ù¤Ê¤Î¤Ç,²¼¤Ç¤«¤Ê¤ê¤Þ¤È¤Þ¤Ã¤Æ½ñ¤¤¤Æ¤·¤Þ¤¤¤Þ¤¹¡£
¤½¤Î¤¿¤á,½ç½ø¤Ë¤Ä¤¤¤Æ´·¤ì¤Æ¤¤¤Ê¤¤Êý¤Ï¤Ä¤é¤¤¤È»×¤¤¤Þ¤¹¡£
¤·¤«¤·,¤³¤ì°Ê¸å(¤Ç¤¤ì¤Ð¼¡²ó¤â),Ã༡±é½¬¤Ê¤ÉÆþ¤ì¤Æ¤¤¤¤Þ¤¹¤Î¤Ç¤À¤ó¤À¤ó¤Ë´·¤ì¤Æ¤¤¤Ã¤Æ¤¯¤À¤µ¤¤.)
Ⱦ½ç½ø½¸¹ç((partially ordered set,ά¤·¤Æ¤è¤¯ poset (¥Ý¡¼¥»¥Ã¥È¤ÈÆɤà)¤È¤¤¤ï¤ì¤ë) ¤È¤Ï, ½¸¹ç ¤È¼¡¤Î (1) (3)¤òËþ¤¹¤ë ¾å¤Î2¹à´Ø·¸ ¤ÎÁÈ ¤Î¤³¤È¤Ç¤¹: Ǥ°Õ¤Î ¤Ë¤Ä¤¤¤Æ,
¤³¤Î¤È¤, ¤Ï½ç½ø´Ø·¸ (order relation),ÆäË( ¾å¤Î)(Ⱦ)½ç½ø((partial) order)¤È¤¤¤¤¤Þ¤¹¡£
¤¬¶õ½¸¹ç¤Î¤È¤¤âÄêµÁ¤Ç¤¤ë¤â¤Î¤È¤·¤Þ¤¹¡£
¤Þ¤¿,ÌÀ¤é¤«¤Ëº®Í𤬵¯¤¤Ê¤¤¾ì¹ç,( )¤òñ¤Ë ¤È½ñ¤¤Þ¤¹¡£
¤ò½¸¹ç¤òÍ×ÁǤȤ¹¤ë½¸¹ç¤È¤¹¤ë¤È,½¸¹ç´Ö¤ÎÊñ´Þ´Ø·¸ ¤ÏÌÀ¤é¤«¤Ë½ç½ø´Ø·¸¤È¤Ê¤ê,
¤ÏȾ½ç½ø½¸¹ç¤Ç¤¹¡£
¤Þ¤¿, ¤ò ¤È¤â½ñ¤¯¤³¤È¤Ë¤·¤Þ¤¹¡£
¤³¤ÎÄêµÁ¤«¤é,Ì¿Âê6(¤½¤Î1)¤Ë¤è¤Ã¤Æ,¥Ö¡¼¥ëÂå¿ô ¤ÇÄêµÁ¤µ¤ì¤¿ ¤Ë´Ø¤·¤Æ, ¤ÏȾ½ç½ø½¸¹ç¤Ë¤Ê¤ê¤Þ¤¹¡£
Ǥ°Õ¤Î½¸¹ç ¤Ë¤Ä¤¤¤Æ,
¤âȾ½ç½ø½¸¹ç¤Ç¤¹¡£
¤òȾ½ç½ø½¸¹ç¤È¤·¤Þ¤¹¡£
¤ò ¤ÎÉôʬ½¸¹ç¤È¤·¤Þ¤¹¡£
¤³¤Î¤È¤,
¤ò ¤ò ¾å¤Ç¹Í¤¨¤¿¤â¤Î¤È¤¹¤ì¤Ð, ¤ÏȾ½ç½ø½¸¹ç¤Ë¤Ê¤ê¤Þ¤¹¡£
¤³¤Î ¤òñ¤Ë, ¤Çɽ¤¹¤³¤È¤Ë¤·¤Þ¤¹¡£
¤Ï
¤ÎÉôʬȾ½ç½ø½¸¹ç¤È¤¤¤¤¤Þ¤¹¡£
¤ò¥Ö¡¼¥ëÂå¿ô ¤ÎÉôʬ±§Ãè¤È¤·¤Þ¤¹¡£
¤ÇÄêµÁ¤µ¤ì¤¿ ¤Ë´Ø¤·¤Æ, ¤Ï ¤ÎÉôʬȾ½ç½ø½¸¹ç¤Ë¤Ê¤ê¤Þ¤¹¡£
¤òȾ½ç½ø½¸¹ç¤È¤·¤Þ¤¹¡£
¤ÎÍ×ÁÇ ¤ÏÁ´¤Æ¤Î ¤Ë¤Ä¤¤¤Æ, ¤È¤Ê¤ë¤È¤,ºÇÂ縵¤È¤¤¤¤¤Þ¤¹¡£
ƱÍͤË, ¤ÎÍ×ÁÇ ¤ÏÁ´¤Æ¤Î
¤Ë¤Ä¤¤¤Æ, ¤È¤Ê¤ë¤È¤,ºÇ¾®¸µ¤È¤¤¤¤¤Þ¤¹¡£
¤Ï¾ï¤ËºÇÂ縵¤Þ¤¿¤ÏºÇ¾®¸µ¤ò»ý¤Ä¤È¤Ï¸Â¤ê¤Þ¤»¤ó.
¤ÎºÇÂ縵¤¬Â¸ºß¤¹¤ë¤È¤¤Ï¤½¤ì¤ò1¤Ç,ºÇ¾®¸µ¤¬Â¸ºß¤¹¤ë¤È¤¤Ï¤½¤ì¤ò0¤Çɽ¤·¤Þ¤¹¡£
Ⱦ½ç½ø½¸¹ç ¤Î,¸µ ¤Ï,
¤¬¤¤¤¨¤ë¤È¤,Èæ³Ó²Äǽ¤Ç¤¢¤ë¤È¤¤¤¤¤Þ¤¹¡£
¤ÎÉôʬ½¸¹ç ¤Ï, ¤ÎÁ´¤Æ¤Î2¤Ä¤Î¸µ¤¬Èæ³Ó²Äǽ¤Ê¤È¤,Ï¢º¿(¤Þ¤¿¤Ï,º¿)(chain) ¤È¤¤¤¤¤Þ¤¹¡£
¼«¿È¤¬Ï¢º¿¤Î¤È¤,
¤òÁ´½ç½ø½¸¹ç (totally ordered set), ¤¢¤ë¤¤¤Ï,Àþ·Á½ç½ø½¸¹ç(linearly ordered set)¤È¤¤¤¤¤Þ¤¹¡£
¤½¤Î¤È¤, ¤Ï ( ¾å¤Î) Á´½ç½ø(total order),¤¢¤ë¤¤¤ÏÀþ·Á½ç½ø(linear order)¤È¤¤¤¤¤Þ¤¹¡£
Ǥ°Õ¤ÎÍ×ÁÇ ¤Ë¤Ä¤¤¤Æ, ¤Þ¤¿¤Ï
¤Î¤¤¤º¤ì¤«¤¬À®¤êΩ¤Ä¤È¤, ¤òÁ´½ç½ø½¸¹ç¤Ç¤¢¤ë¤È¤¤¤¦¤ï¤±¤Ç¤¹¡£
¡ÖǤ°Õ¤ÎÍ×ÁÇ ¤Ë¤Ä¤¤¤Æ, ¤Þ¤¿¤Ï ¤Î¤¤¤º¤ì¤«¤¬À®¤êΩ¤Ä¡×¤È¤¤¤¦¤È¤³¤í¤Ï,
¡ÖǤ°Õ¤ÎÍ×ÁÇ ¤Ë¤Ä¤¤¤Æ,
¡×¤È¤¤¤Ã¤Æ¤â¤«¤Þ¤¤¤Þ¤»¤ó.
¤³¤³¤Ç, ¤Ï
¤Ë¤è¤Ã¤ÆÄêµÁ¤µ¤ì¤Þ¤¹¡£
¾å¤ÈƱÍÍ, ¤ò ¤È¤â½ñ¤¯¤³¤È¤Ë¤·¤Þ¤¹¡£
¼Â¿ôÁ´ÂΤν¸¹ç,ÍÍý¿ôÁ´ÂΤν¸¹ç,À°¿ôÁ´ÂΤν¸¹ç¤Ê¤É¤Ï,ÉáÄ̤νç½ø¤Ç¹Í¤¨¤ÆÁ´½ç½ø½¸¹ç¤Ç¤¹¡£
¤òȾ½ç½ø½¸¹ç ¤ÎÉôʬ½¸¹ç¤È¤·¤Þ¤¹¡£
¤ÎÍ×ÁÇ ¤Ï,Á´¤Æ¤Î
¤Ë¤Ä¤¤¤Æ,
¤òËþ¤¹¤ë¤È¤, ¤Î¾å³¦(²¼³¦)¤È¸Æ¤Ð¤ì,
¤È½ñ¤¤Þ¤¹¡£
¤Ë¾å³¦(²¼³¦)¤¬Â¸ºß¤¹¤ë¤È¤, ¤Ï¾å¤Ë(²¼¤Ë)ͳ¦¤Ç¤¢¤ë¤È¤¤¤¤¤Þ¤¹¡£
¤Ï¾å³¦¤ò»ý¤¿¤Ê¤¤¤³¤È¤â¤¢¤ë¤·,
̵¸Â¸Ä¤Î¾å³¦¤ò»ý¤Ä¤³¤È¤â¤¢¤ê¤Þ¤¹¡£
¤³¤ì¤Ï²¼³¦¤Ë¤Ä¤¤¤Æ¤âƱÍͤǤ¹¡£
ÆäË, ¤¬ºÇ¾®¤Î¾å³¦(ºÇÂç¤Î²¼³¦)¤Ç¤¢¤ë¤È¤, ¤Î¾å¸Â(²¼¸Â)¤È¤¤¤¤¤Þ¤¹¡£
¤½¤ì¤é¤Î±Ñ¸ì¤Ï,¾å³¦(upper bound),
²¼³¦(lower bound),¾å¸Â(supremum),²¼¸Â(infinimum) ¤Ç¤¹¡£
¤Î¾å¸Â(²¼¸Â)¤Ç¤¢¤ë¤È¤,
( ¤Ï ¤ÎÂçʸ»ú)¤Çɽ¤·¤Þ¤¹¡£
¤ò,
¤ä
¤Çɽ¤¹¤³¤È¤â¿¤¤¤Ç¤¹¡£
Ⱦ½ç½ø½¸¹ç ¤ÎÍ×ÁÇ(¸µ) ¤¬, ¤È¤Ê¤ë ¤¬Â¸ºß¤·¤Ê¤¤¤È¤, ¤Î¶ËÂ縵¤È¤¤¤¤¤Þ¤¹¡£
ƱÍͤË, ¤ÎÍ×ÁÇ(¸µ) ¤¬ ¤È¤Ê¤ë ¤¬Â¸ºß¤·¤Ê¤¤¤È¤, ¤Î¶Ë¾®¸µ¤È¤¤¤¤¤Þ¤¹¡£
¶ËÂ縵(¶Ë¾®¸µ)¤Ï¤Ê¤¤¤³¤È¤â¤¢¤ê¤Þ¤¹¤·,1¤Ä¤¢¤ë¤¤¤ÏÊ£¿ô¸Ä¤¢¤ë¤³¤È¤â¤¢¤ê¤Þ¤¹¡£
¤¬ºÇÂ縵(ºÇ¾®¸µ)¤ò»ý¤Ä¤È¤,¤½¤ì¤Ï¤¿¤À°ì¤Ä¤Î¶ËÂ縵(¶Ë¾®¸µ)¤È¤Ê¤ê¤Þ¤¹¡£
¤Á¤ç¤Ã¤È´ó¤êÆ»¤Ç¤¹¤¬,Ⱦ½ç½ø½¸¹ç ¤¬µ¢Ç¼Åª½ç½ø½¸¹ç
(inductively ordered set) ¤Ç¤¢¤ë¤È¤Ï, ¤Ç¤¢¤Ã¤Æ, ¤ÎǤ°Õ¤Î¶õ¤Ç¤Ê¤¤Á´½ç½øÉôʬ½¸¹ç(=Ï¢º¿)¤¬
¾å¤Ëͳ¦¤Ç¤¢¤ë(¾å³¦¤¬Â¸ºß¤¹¤ë)¤Ç¤¢¤ë¤³¤È¤ò¤¤¤¤¤Þ¤¹¡£
¤³¤³¤Ç,¿ô³Ø¤Î¾ÚÌÀ¤ËÎɤ¯ÍѤ¤¤ëÍ̾¤Ê (¥Ä¥©¥ë¥ó) ¤ÎÊäÂê¤ò¾Ò²ð¤·¤Þ¤·¤ç¤¦.¤½¤ì¤Ï,
¡ÖȾ½ç½ø½¸¹ç ¤¬µ¢Ç¼Åª½ç½ø½¸¹ç¤Ê¤é¤Ð, ¤Ï¶ËÂ縵¤ò»ý¤Ä.¡×
¤Ç¤¹¡£
¤³¤ì¤Ï½¸¹çÏÀ¤ÎÁªÂò¸øÍý¤ÈƱÃͤˤʤê¤Þ¤¹¡£
ÁªÂò¸øÍý¤È¤Ï,½¸¹çÏÀ¤ÎǺ¤Þ¤·¤¤(?)
¸øÍý¤Ç,¡Ö2¤Ä¤º¤Ä¸ß¤¤¤ËÁǤʶõ¤Ç¤Ê¤¤½¸¹ç¤«¤é¤Ê¤ë½¸¹ç ¤¬Í¿¤¨¤é¤ì¤Æ¤¤¤ë¤È¤,
¼¡¤Î¾ò·ï¤òËþ¤¿¤¹½¸¹ç ¤¬Â¸ºß¤¹¤ë:Ǥ°Õ¤Î ¤Ë¤Ä¤¤¤Æ,
¤È¤Ê¤ë½¸¹ç ¤¬Â¸ºß¤¹¤ë.¡×
¤È¤¤¤¦¤â¤Î¤Ç¤¹¡£
ÁªÂò¸øÍý¤Ë¤Ï¿§¡¹¤Ê¥Ð¡¼¥¸¥ç¥ó¤¬¤¢¤ê¤Þ¤¹¡£
ÁªÂò¸øÍý¤Ï¾ÚÌÀ¤¹¤ë¤È¤¤ÎÎɤ¤Æ»¶ñ¤Ë¤Ê¤ë¤Î¤Ç¤¹¤¬,Ǻ¤Þ¤·¤¤¤È¤¤¤¦¤Î¤Ï,¤³¤ì¤«¤é,¾ï¼±³°¤Î¤³¤È¤¬Æ³¤½Ð¤»¤ë¤«¤é¤Ç¤¹¡£
¤¿¤È¤¨¤Ð,µå¤òŬÅö¤Ëʬ³ä¤·¤Æ¤Þ¤¿´ó¤»½¸¤á¤ë¤È,¸µ¤Îµå¤ÈÁ´¤¯Æ±¤¸µå¤ò2¤Äºî¤ì¤ë¤È¤¤¤¦,¥Ð¥Ê¥Ã¥Ï¡¦
¥¿¥ë¥¹¥¡¼¤Î¥Ñ¥é¥É¥Ã¥¯¥¹¤¬ÁªÂò¸øÍý¤«¤é¾ÚÌÀ¤Ç¤¤Þ¤¹¡£
¤³¤ì¤Ë¤Ä¤¤¤Æ¤Ï,
º½ÅÄÍø°ìÃø¡Ö¥Ð¥Ê¥Ã¥Ï¡¦¥¿¥ë¥¹¥¡¼¤Î¥Ñ¥é¥É¥Ã¥¯¥¹¡×´äÇȽñŹ¡¡1997ǯ
¤È¤¤¤¦Ëܤ¬¤¢¤ê¤Þ¤¹¡£
º½ÅĤµ¤ó¤Ï¿ô³Ø¼Ô¤È¤·¤ÆÃø̾¤ÊÊý¤Ç¤¹¡£
¤¿¤·¤«,»Ö²ì¹ÀÆóÃø¡Ö̵¸Â¤«¤é¤Î¸÷çê¥Ý¡¼¥é¥ó¥É³ØÇɤοô³Ø¼Ôã¡×ÆüËÜɾÏÀ¼Ò¡¡1988ǯ
¤Ë¤â,¤½¤Îµ½Ò¤¬¤¢¤Ã¤¿¤è¤¦¤Ëµ²±¤·¤Æ¤¤¤Þ¤¹¡£
¤Ï¤Ã¤¤êµ²±¤·¤Æ¤¤¤Þ¤»¤ó¤¬.»Ö²ì¤µ¤ó¤â¿ô³Ø¼Ô¤È¤·¤ÆÃø̾¤ÊÊý¤Ç¤¹¡£
¾å¤Î2ºý¤È¤âÀÎ,½ñŹ¤Ç¥Ñ¥é¥Ñ¥é¤È¸«¤¿¤À¤±¤Ê¤Î¤ÇËÜÅö¤Ë¿äÁ¦¤¹¤Ù¤½ñʪ¤«¤É¤¦¤«¤Ï¤ï¤«¤ê¤Þ¤»¤ó.
Ãø̾¤ÊÊý¤¬½ñ¤¤¤Æ¤ª¤é¤ì¤ë¤Î¤ÇÂç¾æÉפÀ¤È¤Ï»×¤¤¤Þ¤¹¡£
Íνñ¤Ç¤â,¥Ð¥Ê¥Ã¥Ï¡¦¥¿¥ë¥¹¥¡¼¤Î¥Ñ¥é¥É¥Ã¥¯¥¹¤Î¤ß¤Ë¤Ä¤¤¤Æ½ñ¤«¤ì¤¿¤â¤Î¤ò¸«¤¿¤³¤È¤¬¤¢¤ê¤Þ¤¹¡£
Banach-Tarski Pradox ¤È¤¤¤¦¥¿¥¤¥È¥ë¤À¤Ã¤¿¤«¤Ê.˺¤ì¤Þ¤·¤¿.
ÁªÂò¸øÍý¤Ë¤Ä¤¤¤Æ¤Ï,(¿¿ÂÇÅоì!) ÅÄÃæ¾°Éפµ¤ó¤Î, ÅÄÃæ¾°É×Ãø¡ÖÁªÂò¸øÍý¤È¿ô³Ø(ÁýÊäÈÇ)¡×Í·À±¼Ò¡¡1999ǯ
¤Ë¾Ü¤·¤¤µ½Ò¤¬¤¢¤ê¤Þ¤¹¡£
¤Þ¤¿,ÁªÂò¸øÍý¤Î¤ß¤ò°·¤Ã¤¿¿ôÍýÏÀÍý³Ø¤ÎÀìÌç½ñ (Íνñ)
(The Axiom of Choice)¤¬ North-Holland¼Ò¤«¤é2ºý½Ð¤Æ¤¤¤Þ¤¹¡£
ÅÄÃ椵¤ó¤ÎËܤϤޤ¿¤·¤Æ¤â¤ªÁ¦¤á¤Ç¤¹¡£
²æ¡¹¤Î¥Ö¡¼¥ëÂå¿ô¤È¤â´Ø·¸¤¬¤¢¤ê¤Þ¤¹¡£
µ¡²ñ¤¬¤¢¤ì¤Ð¸«¤Æ¤ß¤Æ¤¯¤À¤µ¤¤.(ÅÄÃ椵¤ó¤ÎËܤˤâ¥Ð¥Ê¥Ã¥Ï¡¦¥¿¥ë¥¹¥¡¼¤Î¥Ñ¥é¥É¥Ã¥¯¥¹¤¬,
º£½Ò¤Ù¤¿¤â¤Î¤È¤Ï¤¹¤³¤·°Û¤Ê¤ë¤«¤¿¤Á¤ÇºÜ¤Ã¤Æ¤¤¤Þ¤¹¡£ )
¤³¤Î¥»¥ß¥Ê¡¼¤Ç¤â,¶á¤¤¾Íè,¥Ä¥©¥ë¥ó¤ÎÊäÂê¤òÍѤ¤¤Æ½ÅÍפÊÄêÍý¤ò¾ÚÌÀ¤·¤Þ¤¹¡£
¤µ¤Æ,´ó¤êÆ»¤«¤éËÜÆ»¤ËÌá¤ê¤Þ¤·¤ç¤¦.
Ⱦ½ç½ø½¸¹ç ¤Ë¤ª¤¤¤Æ,Ǥ°Õ¤Î2¸µ ¤Ë¤Ä¤¤¤Æ,
½¸¹ç ¤Î¾å¸Â¤ª¤è¤Ó²¼¸Â¤¬ ( ¤ÎÃæ¤Ç)¸ºß¤¹¤ë¤È¤, ¤ò«(lattice)¤È¤¤¤¤¤Þ¤¹¡£
¶õ½¸¹ç0,¤¢¤ë¤¤¤Ï¤¿¤À°ì¤Ä¤ÎÍ×ÁǤ«¤é¤Ê¤ëȾ½ç½ø½¸¹ç¤â¤½¤ì¤¾¤ì«¤ò¤Ê¤·¤Þ¤¹¡£
Æä˸å¼Ô¤òñ°Ì«¤È¤¤¤¤¤Þ¤¹¡£
¤Î¾å¸Â,²¼¸Â¤ò¤½¤ì¤¾¤ì,
¤Èɽ¤·¤Þ¤¹¡£
+¤È ¤ÎÂؤï¤ê¤Ë,¤½¤ì¤¾¤ì, ¤È ¤È¤«, ¤È ¤ò»È¤¦¤³¤È¤â¿¤¤¤Ç¤¹¡£
«¤Ë´Ø¤·¤Æ¤â,ÁÐÂФθ¶Íý¤¬À®¤êΩ¤Á¤Þ¤¹¡£
(Ãí: ¤ÎÁÐÂÐÌ¿Âê¤Ï, ¤Ç¤¹¡£ )
Ǥ°Õ¤Î½¸¹ç ¤Ë¤Ä¤¤¤Æ,
¤Ï«¤Ë¤Ê¤ê¤Þ¤¹¡£