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¤U¤@­¶: Ring of Polynomials over ¤W¤@­¶: ¤@¨Ç±`¨£ªº Rings «e¤@­¶: ¤@¨Ç±`¨£ªº Rings


The Ring of Integers

§Ú­Ì­º¥ý¤¶²Ð¤j®a³Ì¼ô±xªº ring $ \mathbb {Z}$. ¨ä¹ê¥N¼Æ¤W«Ü¦hªº²z½×³£¬O¬°¤F±´°Q©M¾ã¼Æ¬ÛÃöªº°ÝÃD¦Ó²£¥Íªº, ©Ò¥HÁöµM¦³¨Ç¦P¾Ç¤w¹ï $ \mathbb {Z}$ ªº©Ê½è¬Û·í¤F¸Ñ, §Ú­ÌÁÙ¬O²³æªºÂsÄý¤@¤U, ¥H³Æ¥H«á­n°Q½×¬ÛÃö°ÝÃD®É¥i¥H°µ«Ü¦nªº¹ï·Ó.

¾ã¼Æ¤¤³Ì°ò¥»ªº©w²zÀ³¸Ó´N¬O¾ã¼Æªº¾l¼Æ©w²z Euclid's Algorithm, ´X¥G©Ò¦³¾ã¼Æªº°ò¥»©Ê½è³£¬O¥Ñ¥¦±À¾É¥X¨Óªº. ¨ä¹ê§Ú­Ì¦b«e­±¤w¸g¥Î¹L³o­Ó©w²z¦n´X¦¸¤F, ¤£¹L¬°¤F§¹¾ã©Ê§Ú­ÌÁÙ¬Oµ¹¤@­ÓÃÒ©ú.

Theorem 7.1.1 (Euclid's Algorithm)   µ¹©w¤@¥¿¾ã¼Æ n, ¹ï¥ô·Nªº m $ \in$ $ \mathbb {Z}$, ¬Ò¦s¦b h, r $ \in$ $ \mathbb {Z}$, ¨ä¤¤ 0$ \le$r < n, º¡¨¬ m = h . n + r.

µý ©ú. ³o­Ó©w²z§Ú­Ì²ßºDºÙ¬°¾l¼Æ©w²z, ¦p¦¹ºÙ¥¦·íµM´N¥]§t``°£''³o­Ó·§©À. ¤£¹L¦]¬°§Ú­Ì²¦b¦b½Í ring ªº©Ê½è, §Ú­ÌÁקK¥Î°£ªº·§©À.

­º¥ý¦Ò¼ W = {m - t . n | t $ \in$ $ \mathbb {Z}$} ³o¤@­Ó¶°¦X. ¦]¬° t ¥i¨ú¥ô¦ó¾ã¼Æ, «Ü®e©ö´N¬Ý¥X W ¤@©w¥]§t¤@¨Ç«D­tªº¾ã¼Æ. ¥O r ¬O W ¤¤³Ì¤pªº«D­tªº¾ã¼Æ, ¦]¬° r $ \in$ W, ¥Ñ©w¸qª¾¦s¦b h $ \in$ $ \mathbb {Z}$ º¡¨¬ r = m - h . n. §Ú­Ì³Ì¥D­nªº¥Øªº´N¬O­nÃÒ©ú 0$ \le$r < n.

°²³] r ¤£¦X§Ú­Ìªº±ø¥ó, ¤]´N¬O»¡ r$ \ge$n (§O§Ñ¤F r ¬O«D­t¾ã¼Æªº°²³]). ­Y¦p¦¹, §Ú­Ì¥i±N r ¼g¦¨ r = n + r', ¨ä¤¤ r'$ \ge$ 0. ¦]¦¹§Q¥Î

m = h . n + r = h . n + (n + r') = (h + 1) . n + r',

§Ú­Ì±o¨ì r' = m - (h + 1) . n $ \in$ W. ¦ý 0$ \le$r' < r, ³o©M r ¬O W ¤¤³Ì¤pªº«D­t¾ã¼Æ¬Û¥Ù¬Þ. ¬G±oÃÒ¥»©w²z. $ \qedsymbol$

­nª`·N Theorem 7.1.1 ªºÃÒ©ú§Ú­Ì¥Î¨ì¾ã¼Æ¤W¥i¥H±Æ§Çªº well-ordering principle, ¦]¦¹ÁöµMÃÒ©ú«Ü²³æ, ¦ý¨Ã¤£¯àª½±µ®M¥Î¨ì¤@¯ëªº ring. ¤]´N¬O»¡, ¤@¯ëªº ring ¤£¤@©w¦³©Ò¿×ªº Euclid's Algorithm. ±N¨Ó§Ú­Ì·|¬Ý¨ì¤@¨Ç¯S®íªº integral domain ¤]¦³©Ò¿×ªº Euclid's Algorithm. ³o¼Ëªº integral domain §Ú­Ì·|µ¹¥¦¤@­Ó¦WºÙ: ºÙ¬° Euclidean domain.

±µ¤U¨Ó§Ú­Ì´N¨Ó¬Ý¬Ý Theorem 7.1.1 ªºÅ]¤O¦³¦h¤j§a!

Theorem 7.1.2   ¦b $ \mathbb {Z}$ ¤¤©Ò¦³ªº ideal ³£¬O principle ideal.

µý ©ú. ½Æ²ß¤@¤U©w¸q: ­Y I ¬O¤@­Ó $ \mathbb {Z}$ ªº ideal, §Ú­Ì·Q»¡¦b I ¤¤¦s¦b¤@¤¸¯À a ¨Ï±o

I = $\displaystyle \bigl($a$\displaystyle \bigr)$ = {h . a | h $\displaystyle \in$ $\displaystyle \mathbb {Z}$},

¤]´N¬O»¡ I ¬O©Ò¦³ a ªº­¿¼Æ©Ò¦¨ªº¶°¦X. ­Y¤wª¾£¸¶°¦X¬O¥Ñ¬Y¼Æªº©Ò¦³­¿¼Æ©Ò¦¨ªº¶°¦X, §A­n«ç»ò§ä¥X³o­Ó¼Æ©O? ·íµM¬O§ä¨ä¤¤³Ì¤pªº¥¿¾ã¼Æ¤F!

$ \mathbb {Z}$ ¤¤ªº trivial ideal Z ©M {0}, ¤À§O¥Ñ 1 ©M 0 ¥Í¦¨, ©Ò¥H³£¬O principle ideal. ¦]¦¹§Ú­Ì¥u­n¦Ò¼ $ \mathbb {Z}$ ¤¤ nontrivial proper ideal ´N¥i. °²³] I ¬O $ \mathbb {Z}$ ªº¤@­Ó nontrivial proper ideal, ¥Ñ©ó I$ \ne${0}, ¬G¦s¦b b$ \ne$ 0, ¥B b $ \in$ I. ¥Ñ©ó I ¬O ideal, - b ¤]¦b I ¤¤, ¦]¦¹§Ú­Ìª¾ I ¤¤¥²¦s¦b¥¿¾ã¼Æ. ²¥O a $ \in$ I ¬O I ¤¤³Ì¤pªº¥¿¾ã¼Æ, §Ú­Ì­nÃÒ©ú I = $ \bigl($a$ \bigr)$.

­º¥ý a $ \in$ I, ©Ò¥H¹ï¥ô·Nªº h $ \in$ $ \mathbb {Z}$ ¬Ò¦³ h . a $ \in$ I, ¬Gª¾ $ \bigl($a$ \bigr)$ $ \subseteq$ I. ¦]¦¹§Ú­Ì¶È³Ñ¤U­nÃÒ I $ \subseteq$ $ \bigl($a$ \bigr)$, ´«¥y¸Ü´N¬O­nÃÒ©ú I ¤¤ªº¤¸¯À³£¬O a ªº­¿¼Æ. ¥ô¨ú m $ \in$ I «ç»ò»¡ m ¬O a ªº­¿¼Æ©O? (·íµM´N¬O®³ m °£¥H a ¬Ý¬Ý¾l¼Æ¬O¤°»ò¤F.) §Q¥Î Theorem 7.1.1, §Ú­Ìª¾¦s¦b h, r $ \in$ $ \mathbb {Z}$, 0$ \le$r < a º¡¨¬ r = m - h . a. ¥Ñ©ó m $ \in$ I ¥B h . a $ \in$ I, §Q¥Î I ¬O ideal ª¾ r = m - h . a $ \in$ I. ¦ý¤wª¾ a ¬O I ¤¤³Ì¤pªº¥¿¾ã¼Æ, ¬G±o r = 0, §Y m = h . a $ \in$ $ \bigl($a$ \bigr)$. ¤]´N¬O»¡ I $ \subseteq$ $ \bigl($a$ \bigr)$. $ \qedsymbol$

§Ú­Ì´¿´£¿ô¹L, ¨Ã¤£¬O©Ò¦³ªº ring ¥¦ªº ideal ³£·|¬O principle ideal. ¦pªG¤@­Ó integral domain ¥¦ªº ideal ³£¬O principle ideal, ³o¼Ë¯S§Oªº integral domain §Ú­ÌºÙ¤§¬° principle ideal domain. ª`·N¥H¤W $ \mathbb {Z}$ ¬O principle ideal domain (Theorem 7.1.2) ªº©Ê½è, ¬O¥Ñ $ \mathbb {Z}$ ¬O Euclidean domain (Theorem 7.1.1) ³o­Ó©Ê½è±À¾É¥X¨Óªº.

³o¤@¸`§Ú­Ì¥D­n¬O½Í¾ã¼Æ¤W¤¸¯Àªº¤À¸Ñ, ©Ò¥HÁÙ¬Oµ¹¦]¼Æ, ¤½¦]¼Æ©M³Ì¤j¤½¦]¼Æ¤U¤@­Ó©w¸q.

Definition 7.1.3   ¥O a, b $ \in$ $ \mathbb {Z}$.
  1. ­Y d $ \in$ $ \mathbb {Z}$ ¥B¦s¦b h $ \in$ $ \mathbb {Z}$ ¨Ï±o a = h . d, «hºÙ d ¬O a ªº¤@­Ó divisor, °O°µ d | a.
  2. ­Y c $ \in$ $ \mathbb {Z}$, ¥B c | a ¤Î c | b, «hºÙ c ¬° a, b ªº common divisor.
  3. ­Y d $ \in$ $ \mathbb {Z}$ ¬O a, b ³Ì¤jªº common divisor, «hºÙ d ¬° a, b ªº greatest common divisor.

¤@¯ë³£¬O§Q¥Î©Ò¿×ªºÁÓÂà¬Û°£ªk±N¨â­Ó¼Æªº greatest common divisor ¨D¥X, ¦b³o¸Ì§Ú­Ì±N§Q¥Î Theorem 7.1.2 §ä¨ì greatest common divisor ¨Ã±o¨ì¨ä°ò¥»©Ê½è.

Proposition 7.1.4   µ¹©w a, b $ \in$ $ \mathbb {Z}$, «h¦s¦b d $ \in$ $ \mathbb {N}$ º¡¨¬ $ \bigl($d$ \bigr)$ = $ \bigl($a$ \bigr)$ + $ \bigl($b$ \bigr)$ ¥B d ¬° a, b ªº greatest common divisor

µý ©ú. ¥Ñ Lemma 6.2.1 §Ú­Ìª¾

$\displaystyle \bigl($a$\displaystyle \bigr)$ + $\displaystyle \bigl($b$\displaystyle \bigr)$ = {r . a + s . b | r, s $\displaystyle \in$ $\displaystyle \mathbb {Z}$}

¬O $ \mathbb {Z}$ ªº¤@­Ó ideal. ¥Ñ Theorem 7.1.2 ª¾¦s¦b d $ \in$ $ \mathbb {Z}$ ¨Ï±o $ \bigl($d$ \bigr)$ = $ \bigl($a$ \bigr)$ + $ \bigl($b$ \bigr)$. ¦b³o¸Ì§Ú­Ì¥i¥H­n¨D d ¬O¥¿ªº, ³o¬O¦]¬° -1 ¬O $ \mathbb {Z}$ ªº unit ¬G Lemma 6.5.4 §i¶D§Ú­Ì $ \bigl($d$ \bigr)$ = $ \bigl($-d$ \bigr)$.

±µµÛ§Ú­Ì­nÃÒ©ú³o­Ó d $ \in$ $ \mathbb {N}$ ¬O a, b ªº greatest common divisor. ­º¥ý·íµM¬O­nÃÒ d ¬O a, b ªº common divisor. µM¦Ó¦] a $ \in$ $ \bigl($a$ \bigr)$ $ \subseteq$ $ \bigl($a$ \bigr)$ + $ \bigl($b$ \bigr)$ = $ \bigl($d$ \bigr)$, ¬Gª¾¦s¦b r $ \in$ $ \mathbb {Z}$ ¨Ï±o a = r . d. ¤]´N¬O»¡ d | a. ¦P²z, ¥Ñ b $ \in$ $ \bigl($d$ \bigr)$ ¥i±o d | b. ¬Gª¾ d ¬O a, b ªº common divisor.

¨º¬°¬Æ»ò d ·|¬O a, b ªº common divisor ¤¤³Ì¤jªº©O? ¥Ñ©ó d $ \in$ $ \bigl($d$ \bigr)$ = $ \bigl($a$ \bigr)$ + $ \bigl($b$ \bigr)$, §Ú­Ìª¾¹D¦s¦b m, n $ \in$ $ \mathbb {Z}$ ¨Ï±o d = m . a + n . b. µM¦Ó­Y c ¬O a, b ªº common divisor, §Y c | a ¥B c | b, ª¾¦s¦b r, s $ \in$ $ \mathbb {Z}$ ¨Ï±o a = r . c ¥B b = s . c. ¦]¦¹±o

d = m . (r . c) + n . (s . c) = (m . r + n . s) . c.

¤]´N¬O»¡ c | d. ©Ò¥Hª¾ d ¬O©Ò¦³ a, b ªº common divisor ¤¤³Ì¤jªº. $ \qedsymbol$

Proposition 7.1.4 ¤£¥u§i¶D§Ú­Ì¦p¦ó§ä¨ì greatest common divisor, ¨Æ¹ê¤W¦bÃÒ©ú¤¤§Ú­Ì¤]ÃÒ±o greatest common divisor ªº¨â­Ó­«­n©Ê½è.

Corollary 7.1.5   ¥O a, b $ \in$ $ \mathbb {Z}$ ¥B d ¬° a, b ªº greatest common divisor, «h d ²Å¦X¥H¤U¨â©Ê½è:
  1. ¦s¦b m, n $ \in$ $ \mathbb {Z}$ º¡¨¬ d = m . a + n . b.
  2. °²³] c | a ¥B c | b, «h c | d.

±µ¤U¨Ó§Ú­Ì­n½Í¾ã¼Æªº¤À¸Ñ¤¤³Ì°ò¥»ªº¤¸¯À: ½è¼Æ. ¤j®a³£ª¾¹D¤@­Ó½è¼Æ p ´N¬O¦]¼Æ¥u¦³ 1 ©M¥»¨­ªº¼Æ. §Q¥Î³o­Ó©Ê½è§Ú­Ì¥i±o¨ì­Y p | a . b «h p | a ©Î p | b ³o­Ó©Ê½è, ¦]¦¹¤j®a³£·|®³³o¨âºØ©Ê½è¨Ó§P§O¤@­Ó¼Æ¬O§_¬°½è¼Æ. ¤£¹L¦b¤@¯ëªº ring ³o¨âºØ©Ê½è¬O«Ü¤£¤@¼Ëªº, ©Ò¥H§Ú­Ì¥Î¤£¦Pªº¦W¦r¨ÓºÙ©I.

Definition 7.1.6   ¦Ò¼ $ \mathbb {Z}$ ¤¤ªº¤¸¯À p.
  1. ­Y¹ï¥ô·Nº¡¨¬ d | p ªº d $ \in$ $ \mathbb {Z}$ ¬Ò¦³ d = ±1 ©Î d = ±p, «hºÙ p ¬O¤@­Ó irreducible element.
  2. ­Y¹ï¥ô·Nº¡¨¬ p | a . b ªº a, b $ \in$ $ \mathbb {Z}$ ¬Ò¦³ p | a ©Î p | b, «hºÙ p ¬O¤@­Ó prime element.

«ÜÅãµM³o¨âºØ©w¸q¬O¤£¤@¼Ëªº, ¤£¹L¤U¤@­Ó©w²z§i¶D§Ú­Ì¦b¾ã¼Æ¤¤³o¨âºØ©w¸qªº¤¸¯À¬O¬Û¦Pªº. ¤]¦]¦p¦¹¦b¾ã¼Æ¤¤§Ú­Ì´N²Î¤@ºÙ¤§¬°½è¼Æ (prime).

Proposition 7.1.7   ¦b $ \mathbb {Z}$ ¤¤­Y p ¬O¤@­Ó irreducible element, «h p ¬O¤@­Ó prime element. ¤Ï¤§, ­Y p ¬O¤@­Ó prime element, «h p ¬O¤@­Ó irreducible element.

µý ©ú. ­º¥ý§Ú­ÌÃÒ­Y p ¬O irreducible «h p ¬O prime. ¤]´N¬O»¡°²³]¤wª¾ p ¬O irreducible. ¥ô¨ú p | a . b §Ú­Ì­nÃÒ©ú: p | a ©Î p | b. µM¦Ó p | a . b ªí¥Ü¦s¦b r $ \in$ $ \mathbb {Z}$ ¨Ï±o a . b = r . p. ¦pªG p | a ¨º»ò´N±o¨ì§Ú­Ì­nÃÒªº, ©Ò¥H§Ú­Ì¥u­n°Q½× p$ \nmid$a ªº±¡ªp. ¦¹®É§Ú­Ì¦Ò¼ p, a ªº greatest common divisor ¥O¤§¬° d. ¥Ñ©ó d | p ¬G¥Ñ p ¬O irreducible ªº°²³]ª¾ d = 1 ©Î d = p. µM¦Ó d ¤£¥i¯àµ¥©ó p, §_«h¥Ñ d ¬O p, a ªº common divisor ª¾ p = d | a: ¦¹©M p$ \nmid$a ¥Ù¬Þ. ¦]¦¹ª¾ d = 1, ¥Ñ Corollary 7.1.5 ª¾¦s¦b n, m $ \in$ $ \mathbb {Z}$ º¡¨¬ 1 = n . p + m . a. µ¥¦¡¨âÃä­¼¤W b ±o

b = (n . b) . p + m . (a . b) = (n . b) . p + m . (r . p) = (n . b + m . r) . p,

©Ò¥H p | b.

¤Ï¤§, ­Y¤wª¾ p ¬O¤@­Ó prime element §Ú­Ì­nÃÒ©ú p ¬O irreducible. ¤]´N¬OÃÒ©ú­Y d | p, «h d = ±1 ©Î d = ±p. µM¦Ó d | p ªí¥Ü¦s¦b r $ \in$ $ \mathbb {Z}$ º¡¨¬ p = d . r, ¤]´N¬O»¡ p | d . r. ¬G¥Ñ p ¬O prime ªº°²³], §Ú­Ì±o p | d ©Î p | r. ·í p | d ®É, ¥Ñ­ì¥ý°²³] d | p ª¾ d = ±p. ·í p | r ®É, ªí¥Ü¦s¦b s $ \in$ $ \mathbb {Z}$ º¡¨¬ r = s . p. ¬G¥Ñ p = d . r = d . (s . p) ±o d . s = 1. ¦] d, s $ \in$ $ \mathbb {Z}$, ¬G d . s = 1 ªí¥Ü d = ±1. $ \qedsymbol$

³Ì«á§Ú­Ì¨Ó¬Ý¾ã¼Æ³Ì°ò¥»¤]³Ì­«­nªº°ß¤@¤À¸Ñ©w²z. ¥Ñ©ó¥¿¾ã¼Æ©M­t¾ã¼Æªº¤À¸Ñ¥u®t¤@­Ó­t¸¹, §Ú­Ì¥u»Ý¦Ò¼¥¿¾ã¼Æªº±¡ªp.

Theorem 7.1.8   °²³] a $ \in$ $ \mathbb {N}$ ¥B a > 1, «h¦s¦b p1,..., pr, ¨ä¤¤ pi ¬O¬Û²§ªº prime, º¡¨¬

a = p1n1 ... prnr,    ni $\displaystyle \in$ $\displaystyle \mathbb {N}$,$\displaystyle \forall$i $\displaystyle \in$ {1,..., r}.

¦pªG a ¥i¥H¤À¸Ñ¦¨¥t¥ ªº§Î¦¡ a = q1m1 ... qsms, ¨ä¤¤ qi ¬O¬Û²§ªº prime, «h r = s ¥B¸g¹LÅÜ´«¶¶§Ç¥i±o pi = qi, ni = mi, $ \forall$ i $ \in$ {1,..., r}.

µý ©ú. ³o¤S¬O¤@­Ó¨å«¬ªº¦³Ãö¦s¦b©Ê»P°ß¤@©Êªº©w²z, §Ú­Ì¤´µM¤À¶ $ \qedsymbol$

¨ÓÃÒ¦s¦b©Ê»P°ß¤@©Ê.

­º¥ý¨Ó¬Ý¦s¦b©Ê: ²³æ¨Ó»¡¦s¦b©Ê´N¬O­nÃÒ©ú¨C¤@­Ó¤j©ó 1 ªº¾ã¼Æ³£¥i¥H¼g¦¨¦³­­¦h­Ó(¥i¥H¬Û¦P) prime ªº­¼¿n. ¦pªG a ¥»¨­¬O­Ó prime, «h a = p1 (§Y r = 1, n1 = 1), ±oÃÒ¦s¦b©Ê. ¦pªG a ¤£¬O prime ©O? ¥Ñ Proposition 7.1.7 ª¾ a ¤£¬O irreducible, ¤]´N¬O»¡¦s¦b a1, b1 $ \in$ $ \mathbb {N}$ ¥B a1$ \ne$1, b1$ \ne$1 º¡¨¬ a = a1 . b1. ±µ¤U¨Ó´N¬O¬Ý a1, b1 ¬O¤£¬O prime ¤F. ¦pªG¨ä¤¤¦³¤@­Ó¤£¬O prime, §Ú­Ì´NÄ Äò¤À¸Ñ¤U¥hª½¨ì±o¨ì prime ¬°¤î. ³o­Ó¹Lµ¤@©w·|°±¤U¨Ó¦]¬°¨C¦¸¤À¸Ñ«á±oªº¼Æ¶V¨Ó¶V¤p. ·íµM³Ì«á´N¥i¥H±N a ¼g¦¨¤@¨Ç prime ªº­¼¿n¤F. ³o¼ËªºÃÒ©ú¤è¦¡, ¬Û«H¤j®a·|¦³¤@ºØ»¡¤£²M·¡ªº·Pı, ©Ò¥H§Ú­ÌÁÙ¬O¥Î¤ñ¸û¼Æ¾Çªº¤èªk¨ÓÃÒ©ú. ·í a = 2 ®É¥Ñ©ó 2 ¬O prime, ©Ò¥H¦b³o±¡ªp¦s¦b©Ê¬O¹ïªº. ±µµÛ°²³]¹ï©Ò¦³¤¶©ó 2 ©M a - 1 ªº¾ã¼Æ¦s¦b©Ê¬O¹ïªº. ¦pªG a ¬O prime, ¨º¦s¦b©Ê¦ÛµM¦¨¥ß, ¦pªG a ¤£¬O prime, «h¥Ñ Proposition 7.1.7 ª¾ a = a1 . b1 ¨ä¤¤ a1, b1 $ \in$ $ \mathbb {N}$ ¥B 1 < a1 < a ¤Î 1 < b1 < a. ¬G§Q¥ÎÂk¯Ç°²³]ª¾ a1 ©M b1 ³£¥i¼g¦¨¦³­­¦h­Ó prime ªº­¼¿n, ©Ò¥H±oÃÒ a ¤]¥i¥H¼g¦¨¦³­­¦h­Ó prime ªº­¼¿n.

§Ú­Ì¨ÌµM¥ÎÂk¯ÇªkÃҰߤ@©Ê, °²³]

a = p1n1 ... prnr = q1m1 ... qsms,

¨ä¤¤ p1,..., pr ¬O¨â¨â¬Û²§ªº prime, ¥B q1,..., qs ¤]¬O¨â¨â¬Û²§ªº prime. ¥Ñ©ó p1 ¬O prime, ¬G¥Ñ p1 | a = q1m1 ... qsms ª¾¦s¦b¬Y­Ó j $ \in$ {1,..., s} º¡¨¬ p1 | qj. ÅÜ´«¤@¤U¶¶§Ç§Ú­Ì¥i¥H°²³] p1 | q1. ¥Ñ©ó q1 ¬O prime, ¥Ñ Proposition 7.1.7 ª¾ q1 ¬O irreducible. ´«¥y¸Ü»¡, q1 ªº divisor ¥u¯à¬O ±1 ©Î ±q1. ¬G¥Ñ p1 | q1 ª¾ p1 = q1. ²¦b¦Ò¼

$\displaystyle {\frac{a}{p_1}}$ = p1n1 - 1 ... prnr = q1m1 - 1 ... qsms.

¥Ñ©ó a/p1 < a, ¬G§Q¥Î°ß¤@©ÊªºÂk¯Çªk°²³]§Ú­Ì±o r = s ¥B p1 = q1,..., pr = qr ¥H¤Î n1 = m1, n2 = m2,..., nr = mr, ¬G±oÃҰߤ@©Ê.

¦pªG¤@­Ó integral domain ¦³©M $ \mathbb {Z}$ ¤@¼Ë¨C­Ó¤¸¯À³£¥i¥H°ß¤@¼g¦¨¤@¨Ç irreducible element ªº­¼¿nªº©Ê½è, §Ú­Ì«KºÙ¦¹ integral domain ¬°¤@­Ó unique factorization domain.


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¤U¤@­¶: Ring of Polynomials over ¤W¤@­¶: ¤@¨Ç±`¨£ªº Rings «e¤@­¶: ¤@¨Ç±`¨£ªº Rings
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