¤U¤@¶: Quotient Field of an
¤W¤@¶: ¤@¨Ç±`¨£ªº Rings
«e¤@¶: Ring of Polynomials over
«e¤@³¹¸`ªºµ²ªG·íµM³£¥i¥H®M¥Î¨ì¦³²z«Y¼Æªº polynomials,
¦ý«o¤£¯à§¹§¹¾ã¾ãªº®M¥Î¨ì¾ã«Y¼Æªº polynomials.
³o¤@³¹§Ú̱N¬Ý¬Ý¾ã«Y¼Æ©M¦³²z«Y¼Æ polynomials ªº²§¦P.
³Ì«á¦A§Q¥Î«e±³¹¸`´£¨ì¾ã¼Æªº°ß¤@¤À¸Ñ©Ê¥H¤Î¦³²z«Y¼Æªº polynomial ring
ªº°ß¤@¤À¸Ñ©Ê, ±o¨ì¾ã«Y¼Æªº polynomial ring ªº°ß¤@¤À¸Ñ©Ê.
§ÚÌ¥O
[x] ªí¥Ü©Ò¦³¦³²z«Y¼Æ polynomials ©Ò¦¨ªº¶°¦X¥B¥O
[x]
ªí¥Ü©Ò¦³¾ã«Y¼Æ polynomials ©Ò¦¨ªº¶°¦X. «e±¤wª¾
[x]
¥Î¤@¯ëªº¥[ªk©M¼ªk¥i§Î¦¨¤@Ó ring, §Ú̺٤§¬° polynomial ring over
. ¦P²z§Ṳ́]¥i¥HÃÒ¥X
[x] ¤]¬O¤@Ó ring, §Ú̺٤§¬°
polynomial ring over
.
[x] ªº 0 ©M 1 ©M
[x] ªº 0 ©M 1 ¬Û¦P. §Ṳ́]¥i¦b
[x] ¤¤©w¸q degree (¤Ï¥¿¥i¥H§â
[x] ¬Ý¦¨
[x] ªº¤l¶°¦X).
©Ò¥H§Q¥Î©M Lemma 7.2.3 ¬Û¦PªºÃÒ©ú, §ÚÌ¥i±o
[x] ¬O¤@Ó
integral domain.
[x] ©M
[x] ³Ì¤jªº¤£¦P¬O
[x] ¤¤©Ò¦³«D
0 ªº±`¼Æ³£¬O unit, µM¦Ó
[x] ¤¤¥u¦³ ±1 ³o¨âÓ±`¼Æ¬°¨ä
unit. ³o¬O¦]¬°§Q¥Î Lemma 7.2.3 ªºÃÒ©ú§Ú̪¾¹D
[x] ¤¤ªº
unit ¨ä degree ¤@©w¬O 0, ©Ò¥H¥u¦³±`¼Æ¤ ¥i¯à¬O
[x] ªº unit,
µM¦Ó¦]§ÚÌ¥u¦Ò¼¾ã«Y¼Æ, ©Ò¥H¦b
¤¤ªº unit ¤ ¥i¥H¬O
[x] ªº
unit, ¤]´N¬O ±1. ¦]¦¹³o¸Ì§ÚÌ¥²¶·´£¿ô¤j®a, ¦b
[x]
¤¤½Í¤À¸Ñ®Én±N±`¼Æªº¤À¸Ñ¦C¤J¦Ò¼.
¦b Remark 7.2.5 ¤¤§ÚÌ´£¤Î
[x] ¤¤¨Ã¨S¦³¾l¦¡©w²z,
©Ò¥H¦b
[x] ¤¤¥i§Q¥Î¾l¦¡©w²z±o¨ìªº©Ò¦³ ideal ³£¬O principle
ideal (Theorem 7.2.6) ¹ï
[x] ´N¤£¤@©w¹ï.
¨Æ¹ê¤W§ÚÌ¥i¥H¦b
[x] ¤¤§ä¨ì¤@Ó (·íµM¤£¥u¤@Ó) ideal ¥¦¤£¬O
principle ideal.
Example 7.3.1
§ÚÌn»¡©ú¦b
[
x] ¤¤
I = (2) + (
x) ¤£¬O principle ideal. °²³]
I
¬O principle ideal, §Y¦s¦b
f (
x)
[
x] ¨Ï±o
I =
f (
x)
.
§Q¥Î 2
I, §Ú̱o¨ì
2
f (
x)
, ¤]´N¬O¦s¦b
h(
x)
[
x]
º¡¨¬
2 =
h(
x)
. f (
x). §Q¥Î degree °¨¤W¥iª¾
deg(
f (
x)) = 0,
¤]´N¬O»¡
f (
x) ¬O¤@Ó±`¼Æ
c . ²¦b§Q¥Î
x I =
c
ª¾¦s¦b
g(
x)
[
x] ¨Ï±o
x =
c . g(
x). ª`·N
c . g(
x)
³o¤@Ó¦h¶µ¦¡¥¦ªº«Y¼Æ¤@©w¬O
c ªº¿¼Æ (§O§Ñ¤F
g(
x)
[
x], ©Ò¥H
g(
x) ªº«Y¼Æ³£¬O¾ã¼Æ). ¦]¦¹¥Ñ
x =
c . g(
x) ª¾
x
³o¤@Ó¦h¶µ¦¡ªº«Y¼ÆÀ³¸Ó¬O
c ªº¿¼Æ. µM¦Ó
x ³o¤@Ó¦h¶µ¦¡¥u¦³
x
³o¤@¶µ¥B¨ä«Y¼Æ¬O 1, ¬G±o
c | 1, ¤]´N¬O
c = ±1. ¦]
c ¬O
unit, Lemma
6.2.4 §i¶D§ÚÌ
I =
c =
[
x], ´«¥y¸Ü»¡
1
I =
2
+
x. §Q¥Î
2
+
x ªº©w¸qª¾³oªí¥Ü¦s¦b
n(
x),
m(
x)
[
x] ¨Ï±o
1 = 2
. n(
x) +
x . m(
x). ¤£¹L
x . m(
x) ¨S¦³±`¼Æ¶µ, ¦Ó
2
. n(
x) ªº±`¼Æ¶µ¤@©w¬O 2 ªº¿¼Æ, ©Ò¥H
2
. n(
x) +
x . m(
x) ªº±`¼Æ¶µ¤@©w¤£¥i¯à¬° 1. ¬G·í
n(
x),
m(
x)
[
x] ®É
1 = 2
. n(
x) +
x . m(
x) ¤£¥i¯à¦¨¥ß.
¦¹¥Ù¬Þµo¥Í©ó§Ú̪º°²³]
I ¬O principle ideal, ¬G±o
I =
2
+
x ¤£¥i¯à¬O
[
x] ªº principle ideal.
¦n¤F¬JµM
[x] ¤¤ªº ideal ¤£¤@©w¬O principle ideal
¨º»ò§ÚÌ´N¤£¯à¾Ç Proposition 7.2.11 ªº¤èªk±o¨ì
[x] ¤¤ªº
irreducible element ´N¬O prime element ¤F.
¤£¯à¥Î³o®M¤èªk¨Ã¤£ªí¥Üµ²ªG·|¿ù,
¦]¬°¦³¥i¯à¥Î¥t¤@®M¤èªk¥i¥H±o¨ì·Qnªºµ²ªG°Ú!
¨S¿ù§Ú̱N·|ÃÒ©ú¦b
[x] ¤¤ªº irreducible element ©M prime
element ¬O¬Û¦Pªº, ¤£¹L§ÚÌnµo®i¥t¤@®Mªº¤èªk¨Ó±o¨ì.
³oÓ¤èªk¨ä¹ê´N¬On§JªA«e±´£¨ì
[x] ©M
[x] ³Ì¤jªº¤£¦P´N¬O¦b
[x] ¤¤n¦Ò¼±`¼Æªº¤À¸Ñ. µ¹©w
f (x) = a0 + a1x + ... + anxn [x] n±N f (x) ¤À¸Ñ¦¨ degree ¤ñ¸û¤pªº polynomials
¬Û¼¤§«e, ¥i¥H¥ý¦Ò¼¥i¤£¥i¥H´£¥X¤@Ó±`¼Æ¥X¨Ó (¦]¬°Y³oÓ±`¼Æ¤£¬O
±1 ¨º»ò¦b
[x] ¤¤³o´Nºâ¬O¤@Ó``¦³®Ä''ªº¤À¸Ñ).
¥i¥H´£¥X¬Æ»ò±`¼Æ¥X¨Ó©O? ¤j®a³£·|·Q¨ì´£¥X¨º¨Ç«Y¼Æ
a0, a1,..., an
ªº³Ì¤j¤½¦]¼Æ§a! ©Ò¥H§Ú̦³¥H¤U²³æ¦ý«n¤§µ²ªG.
Lemma 7.3.2
Y
f (
x)
[
x] ¬O¤@Ó«D 0 ªº polynomial, «h
f (
x) ¥i°ß¤@¼g¦¨
f (
x) =
c . f*(
x), ¨ä¤¤
c ,
f*(
x)
[
x] ¥B
f*(
x)
ªº«Y¼Æªº³Ì¤j¤½¦]¼Æ¬O 1.
µý ©ú.
º¥ýÃÒ©ú¦s¦b©Ê: Y
f (
x) =
a0 +
a1x +
... +
anxn, ¥O
d = gcd(
a0,
a1,...,
an). ¥Ñ³Ì¤j¤½¦]¼Æªº©Ê½èª¾
a0 =
d . b0,
a1 =
d . b1,...,
an =
d . bn ¥B
gcd(
b0,
b1,...,
bn) = 1. ¬G¥i±N
f (
x) ¼g¦¨
d . (
b0 +
b1x +
... +
bnxn) ¬°©Òn¨Dªº§Î¦¡.
±µµÛÃÒ©ú°ß¤@©Ê: °²³]
f (x) = c . f*(x), ¨ä¤¤
c ¥B
f*(x) [x]. ±N c ¼¤J f*(x) ªº¦U¶µ«Y¼Æ¤¤, ª¾ f (x)
ªº©Ò¦³«Y¼Æ
a0, a1,..., an ³£·|¬O c ªº¿¼Æ. ¤]´N¬O c ¬O
a0, a1,..., an ªº¤½¦]¼Æ. ¦pªG
cd = gcd(a0, a1,..., an),
«h f*(x) ªº«Y¼Æ¤¤·|¦³ d /c ³o¤@Ó¤£¬O 1 ªº¤½¦]¼Æ, ¦¹©M
f*(x) ªº¦U¶µ«Y¼Æªº³Ì¤j¤½¦]¼Æ¬° 1 ¬Û¥Ù¬Þ. ¬G±o d = c, ¤]´N¬O»¡
d . f*(x) = d . (b0 + b1x + ... + bnxn). ³Ì«á¦]
[x] ¬O
integral domain, §Ú̱o
f*(x) = b0 + b1x + ... + bnxn.
¦³¤F Lemma 7.3.2, §Ú̦³¥H¤Uªº©w¸q.
Definition 7.3.3
Y
f (
x)
[
x] ¥i¼g¦¨
f (
x) =
c . f*(
x), ¨ä¤¤
c ,
f*(
x)
[
x] ¥B
f*(
x) ªº«Y¼Æªº³Ì¤j¤½¦]¼Æ¬O 1. «hºÙ
c ¬°
f (
x) ªº
content, °O¬°
c(
f ). Y
f (
x)
[
x] ¥B
c(
f )= 1, «hºÙ
f (
x) ¬O¤@Ó
primitive polynomial.
¨ä¹ê c(f ) ´N¬O f (x) ªº©Ò¦³«Y¼Æªº³Ì¤j¤½¦]¼Æ. Lemma 7.3.2
§i¶D§ÚÌ»¡¥ô·Nªº
f (x) [x] ³£¥i¥H¼g¦¨¨ä content ¼¤W¤@Ó
primitive polynomial. §ÚÌ¥i¥H±N Lemma 7.3.2 ±À¼s¨ì
[x]
¤¤.
Proposition 7.3.4
Y
f (
x)
[
x] ¬O¤@Ó«D 0 ªº polynomial, «h
f (
x) ¥i°ß¤@¼g¦¨
f (
x) =
c . f*(
x), ¨ä¤¤
c ,
c > 0 ¥B
f*(
x)
[
x]
¬O¤@Ó primitive polynomial.
µý ©ú.
º¥ýÃÒ©ú¦s¦b©Ê: Y
f (
x) =
a0 +
a1x +
... +
anxn, ¨ä¤¤
ai .
§ÚÌ¥i§ä¨ì¤@¥¿¾ã¼Æ
m ¨Ï±o
m . f (
x)
[
x] (¤ñ¤è»¡¥O
m ¬°
³o¨Ç
ai ¤À¥Àªº¼¿n). ¬JµM
m . f (
x)
[
x] ¥Ñ Lemma
7.3.2 ªº¦s¦b©Êª¾¦s¦b¥¿¾ã¼Æ
a ¥H¤Î
f*(
x)
[
x] ¨ä¤¤
f*(
x) ¬O primitive polynomial, ¨Ï±o
m . f (
x) =
a . f*(
x).
¬G±o
f (
x) =
. f*(
x)
¬°©Òn¨Dªº§Î¦¡.
¦Ü©ó°ß¤@©Ê§ÚÌ°²³]
f (x) = d . f*(x) = d' . g(x) ¨ä¤¤ d, d'
³£¬O¥¿ªº¦³²z¼Æ¦Ó
f*(x), g(x) [x] ³£¬O primitive polynomials.
±N d ©M d' ¤À§O¼g¦¨ a/b ©M a'/b', ¨ä¤¤
a, a', b, b' .
§ÚÌ¥i±o
(a . b') . f*(x) = (a' . b) . g(x).
§O§Ñ¤F
(
a . b')
. f*(
x),(
a' . b)
. g(
x)
[
x] ¤S¦]
a . b',
a' . b ¥B
f*(
x),
g(
x) ³£¬O primitive
polynomial, ¥Ñ Lemma
7.3.2 ªº°ß¤@©Êª¾:
a . b' =
b . a'
(§Y
d =
d') ¥B
f*(
x) =
g(
x). ¬G±oÃҰߤ@©Ê.
¥Ñ Proposition 7.3.4, §ÚÌ¥i¥H§â content ªº©w¸q±À¼s¨ì
[x],
¥H«á§Ú̱N·|§â¥ô·Nªº
f (x) [x] ¼g¦¨
f (x) = c(f ) . f*(x),
¨ä¤¤
0 < c(f ) ¬O f (x) ªº content,
f*(x) [x] ¬O¤@Ó
primitive polynomial.
·í
f (x), g(x) [x], npºâ
f (x) . g(x) ªº content,
¨ä¹ê¬O«Ü½ÆÂøªº. §ÚÌ¥²¶·§â¨âÓ polynomial ¼¶, ²¾¶µ¾ã²z,
¦A³q¤À§ä³Ì¤j¤½¦]¼Æ. §ÚÌ·íµM§Æ±æ
f (x) . g(x) ªº content ¥i¥H¥Ñ
f (x) ©M g(x) ªº contents ª½±µ¨D¥X´N¦n¤F.
Åý§ÚÌ¥ý¬Ý¤@Ó¯S®í¨Ò¤l´N¬O f (x) ©M g(x) ªº contents ³£¬O 1
ªº±¡ªp.
Lemma 7.3.5 (Gauss Lemma)
Y
f (
x),
g(
x)
[
x] ³£¬O primitive polynomials, «h
f (
x)
. g(
x) ¤]¬O¤@Ó primitive polynomial.
µý ©ú.
³]
f (
x) =
anxn +
... +
a1x +
a0,
g(
x) =
bmxm +
... +
b1x +
b0,
§ÚÌn¥Î¤ÏÃÒªkÃÒ©úY
c(
f )=
c(
g) = 1, «h
c(
f . g) = 1. °²³]
c(
f . g) =
d1, ¨ú¤@½è¼Æ
p ¨Ï±o
p |
d, ¤]´N¬O
p ¾ã°£
f (
x)
. g(
x) ªº©Ò¦³«Y¼Æ. µM¦]
c(
f )=
c(
g) = 1, ¬G¥²¦s¦b
ai,
bj ¨Ï±o
pai ¥B
pbj. ¥O
r ¬O³Ì¤pªº¾ã¼Æ¨Ï±o
par (¤]´N¬O
par, ¦ý¹ï¥ô·Nªº
i <
r,
p |
ai),
¦P¼Ëªº¥O
s ¬O³Ì¤pªº¾ã¼Æ¨Ï±o
pbs. ²Æ[¹î
f (
x)
. g(
x)
ªº
xr + s ¶µ«Y¼Æ:
ai . bj.
°£¤F
ar . bs ¥H¥ , ¨ä¥L¶µªº
ai . bj n¤£¬O
i <
r ´N¬O
j <
s. §_«hY
i >
r ¥B
j >
s ¨º»ò
i +
j >
r +
s ´N¤£¥i¯à²Å¦X
i +
j =
r +
s ¤F. ¦pªG
i <
r
¥Ñ·íªì
r ªº¿ï¨úª¾
p |
ai, ¬Gª¾¦¹±¡ªp¤U
p |
ai . bj.
¦P²z, Y
j <
s ¤]¥i±o
p |
ai . bj. Á`¦Ó¨¥¤§,
f (
x)
. g(
x) ªº
xr + s ¶µªº«Y¼Æ°£¤F
ar . bs ¥ ¨ä¥Lªº
ai . bj ³£¥i³Q
p ¾ã°£. µM¦Ó·íªì°²³]
par ¥B
pbs,
¬Gª¾
par . bs. ¤]´N¬O»¡
f (
x)
. g(
x) ªº
xr + s
¶µªº«Y¼Æ¤£¥i³Q
p ¾ã°£. ³o©M·íªì°²³]
p ¥i¾ã°£
f (
x)
. g(
x)
ªº¨C¤@¶µªº«Y¼Æ¬Û¥Ù¬Þ. ¬Gª¾¤£¥i¯à
c(
f . g)
1, ©Ò¥H
f (
x)
. g(
x) ¤]¬O primitive polynomial.
¦³¤F Gauss Lemma ¹ï©ó¤@¯ëªº
f (x), g(x) [x],
§Ú̫ܧ֪º´N¥i¥Hpºâ¥X
c(f . g).
Proposition 7.3.6
Y
f (
x),
g(
x)
[
x] ³£¬O«D 0 ªº polynomial, «h
c(f . g) = c(f ) . c(g).
µý ©ú.
¥Ñ Lemma
7.3.4 ª¾¥i±N
f (
x) ©M
g(
x) ¤À§O¼g¦¨
f (
x) =
c(
f )
. f*(
x) ©M
g(
x) =
c(
g)
. g*(
x), ¨ä¤¤
f*(
x) ©M
g*(
x) ³£¬O
primitive polynomials. ¬G±o
f (
x)
. g(
x) =
c(
f )
. c(
g)
. f*(
x)
. g*(
x)
.
¦A¥Ñ Lemma
7.3.4 ª¾
f (
x)
. g(
x) ¥i°ß¤@¼g¦¨
c(
f . g)
. h(
x)
¨ä¤¤
h(
x) ¬O primitive polynomial. µM¦Ó Lemma
7.3.5 §i¶D§ÚÌ
f*(
x)
. g*(
x) ¬O primitive polynomial, ¬G¥Ñ°ß¤@©Êª¾
f*(
x)
. g*(
x) =
h(
x) ¥B
c(
f )
. c(
g) =
c(
f . g).
±µ¤U¨Ó§ÚÌn½Í
[x] ¤Wªº¤À¸Ñ, º¥ýn°Ï¤À¤@¤U¦b
[x] ©M
[x] ¤¤ªº¾ã°£·§©À. µ¹©w
f (x), g(x) [x], §ÚÌ»¡
f (x) | g(x) in
[x] ªí¥Ü¦s¦b
h(x) [x] º¡¨¬
g(x) = h(x) . f (x). ¦Ó§ÚÌ»¡
f (x) | g(x) in
[x] ªí¥Ü¦s¦b
l (x) [x]
º¡¨¬
g(x) = l (x) . f (x). ³o¸Ì³Ì¤jªº¤£¦P¦b©ó h(x) n¨D¸¨¦b
[x], ¦Ó l (x) n¦b
[x] §Y¥i. ©Ò¥H¦³¥i¯àµo¥Í
f (x) | g(x) in
[x] ¦ý
f (x)g(x) in
[x] ªºª¬ªp.
Lemma 7.3.7
°²³]
f (
x),
g(
x)
[
x], ¥B
f (
x) ¬O¤@Ó primitive polynomial, «h
f (
x) |
g(
x) in
[
x] Y¥B°ßY
f (
x) |
g(
x) in
[
x].
µý ©ú.
°²³]
f (
x) |
g(
x) in
[
x] ªí¥Ü¦s¦b
h(
x)
[
x] º¡¨¬
g(
x) =
h(
x)
. f (
x). µM¦Ó
h(
x)
[
x] ·íµM±o
h(
x)
[
x],
¬Gª¾
f (
x) |
g(
x) in
[
x]. (ª`·N³o³¡¤À§Ṳ́£»Ýn
f (
x) ¬O
primitive ªº°²³].)
¤Ï¤§, Y
f (x) | g(x) in
[x], ªí¥Ü¦s¦b
l (x) [x] º¡¨¬
g(x) = l (x) . f (x). §Ú̧Ʊæ¯àÃÒ±o
l (x) [x]. §Q¥Î Lemma
7.3.4 ±N l (x) ¼g¦¨
l (x) = c(l ) . l*(x), ¨ä¤¤ l*(x) ¬O
primitive polynomials. ¬G±o
g(x) = c(l ) . (l*(x) . f (x)). ¦]¬°
f (x) ©M l*(x) ³£¬O primitive polynomials, ¬G§Q¥Î Lemma
7.3.5 ª¾
l*(x) . f (x) ¬O primitive polynomial. ¦A§Q¥Î
Lemma 7.3.4 ªº°ß¤@©Êª¾ c(g) = c(l ). ¦]
c(g) , ¬G±o
c(l ) , ¥B¤S
l*(x) [x], ¬G¥Ñ
l (x) = c(l ) . l*(x)
±o
l (x) [x].
¦P¼Ëªº, §Ṳ́]n°Ï¤À¤@¤U¦b
[x] ©M
[x] ¤¤¤À¸Ñªº¤£¦P. Y
f (x) [x] §ÚÌ»¡ f (x) ¦b
[x] ¥i¤À¸Ñªí¥Ü f (x) ¥i¼g¦¨
f (x) = g(x) . h(x), ¨ä¤¤
g(x), h(x) [x] ¥B
deg(g(x)) ©M
deg(h(x)) ¬Ò¤p©ó
deg(f (x)). ¦ý³o¨Ã¤£ªí¥Ü f (x) ¥i¥H¦b
[x] ¤¤¤À¸Ñ¦¨
f (x) = m(x) . n(x), ¨ä¤¤
m(x), n(x) [x].
¤£¹L¤U¤@Ó Lemma §i¶D§Ú̳o¬O¿ì±o¨ìªº.
Lemma 7.3.8
°²³]
f (
x)
[
x] ¥B
f (
x) =
g(
x)
. h(
x) ¨ä¤¤
g(
x),
h(
x)
[
x], «h¦s¦b
m(
x),
n(
x)
[
x] º¡¨¬
f (
x) =
m(
x)
. n(
x) ¥B
deg(
m(
x)) = deg(
g(
x)) ¤Î
deg(
n(
x)) = deg(
h(
x)).
µý ©ú.
§Q¥Î Lemma
7.3.4 ª¾
g(
x) =
c(
g)
. g*(
x) ¥B
h(
x) =
c(
h)
. h*(
x) ¨ä¤¤
g*(
x),
h*(
x)
[
x] ¥B³£¬O primitive polynomial.
§Q¥Î Proposition
7.3.6 ª¾
c(g) . c(h) = c(g . h) = c(f ),
µM¦Ó
f (
x)
[
x], ¬G
c(
g)
. c(
h) =
c(
f )
. ¦]¦¹Y¥O
m(
x) =
c(
g)
. c(
h)
. g*(
x)
[
x] ¤Î
n(
x) =
h*(
x)
[
x], «h
f (x) |
= |
g(x) . h(x) = c(g) . g*(x) . c(h) . h*(x) |
|
|
= |
c(g) . c(h) . g*(x) . h*(x) |
|
|
= |
m(x) . n(x). |
|
¤S
deg(m(x)) = deg(g*(x)) = deg(g(x)) ¥B deg(n(x)) = deg(h*(x)) = deg(h(x)).
¤Ï¤§Y f (x) ¦b
[x] ¥i¥H¤À¸Ñ¦¨
f (x) = m(x) . n(x), ¨ä¤¤
m(x), n(x) [x], ¥B m(x), n(x) ¤£¬O
[x] ¤¤ªº unit. ¨º»ò
¤j®a¤@©w»¬°¥Ñ©ó m(x), n(x) ¤]¦b
[x] ¤¤©Ò¥H f (x) ¦b
[x]
¤¤¥i¥H¤À¸Ñ. ¨ä¹ê¤£µM, ¦]¬° m(x), n(x) ¦b
[x] ¤¤¤£¬O unit,
¦ý¥i¯à¦b
[x] ¤¤´N¬O unit ¤F. ¨Ò¦p 2x + 2 ¦b
[x] ¬O
irreducible ¦ý¦b
[x] ¤¤
2x + 2 = 2 . (x + 1), ¦Ó¥B 2 ©M x + 1
¦b
[x] ¤¤³£¤£¬O unit (¦ý 2 ¦b
[x] ¬O unit), ©Ò¥H 2x + 2
¦b
[x] ¨Ã¤£¬O irreducible. ±q³o¸Ì¬Ý¥X
[x] ¤¤ªº irreducible
element ©M
[x] ªº irreducible element ¤£¦P.
¦^ÅU¤@¤U§ÚÌ©w¸q©Ò¿×ªº irreducible element ¬O¤@Ó¤¸¯À¥¦ªº divisor
¥u¦³ unit ©M ¥»¨¼¤W unit ³o¨âºØ§Î¦¡. ¥Ñ©ó
[x] ¤¤ªº unit ¥u¦³
1 ©M -1 ©Ò¥H§Ú̦³¥H¤Uªº©w¸q.
Definition 7.3.9
¥O
p(
x)
[
x]
- Y p(x) ¦b
[x] ¤¤ªº divisor ¥u¦³ ±1 ©M ±p(x),
«hºÙ p(x) ¬O
[x] ªº irreducible element.
- Y¹ï©Ò¦³º¡¨¬
p(x) | f (x) . g(x) ªº
f (x), g(x) [x]
³£¦³
p(x) | f (x) ©Î
p(x) | g(x) «hºÙ p(x) ¬O
[x] ªº
prime element.
¥Ñ³oÓ©w¸q§ÚÌ°¨¤W±o¨ì¥H¤Uªº Lemma.
Lemma 7.3.10
°²³]
p(
x)
[
x] ¥B
deg(
p(
x)) > 0.
- Y p(x) ¬O¤@Ó irreducible element, «h p(x) ¬O¤@Ó primitive
polynomial.
- Y p(x) ¬O¤@Ó prime element, «h p(x) ¬O¤@Ó primitive
polynomial.
µý ©ú.
(1) °²³]
p(
x) ¬O irreducible. ¦]
p(
x) =
c(
p)
. p*(
x), ¨ä¤¤
c(
p)
[
x] ¥B
p*(
x)
[
x], ©Ò¥H
c(
p) ¬O
p(
x) ªº¤@Ó divisor. ¥Ñ
p(
x) ¬O irreducible ¤Î
deg(
p*(
x)) = deg(
p(
x)) > 0 ª¾
c(
p) = 1, ¬G±o
p(
x) ¬O primitive.
(2) °²³] p(x) ¬O prime. ¦]
p(x) = c(p) . p*(x), ¬Gª¾
p(x) | c(p) . p*(x). ¥Ñ p(x) ¬O prime ªº°²³], ª¾
p(x) | c(p) ©Î
p(x) | p*(x). ¥Ñ©ó
deg(p(x)) > 0 ª¾¤£¥i¯à
p(x) | c(p).
¬G±o
p(x) | p*(x). ¤]´N¬O»¡¦s¦b
(x) [x] ¨Ï±o
p*(x) = (x) . p(x). ¬G±o
p*(x) = (x) . c(p) . p*(x). §Q¥Î
[x] ¬O integral domain ¤Î
p*(x) 0 ª¾
(x) . c(p) = 1. ¤]´N¬O»¡
(x) ©M
c(p) ¬O
[x] ªº unit. ¦ý¥Ñ©w¸q c(p) ¬O¥¿¾ã¼Æ, ¬G±o
(x) = c(p) = 1. ¤]´N¬O»¡ p(x) ¬O primitive.
¦p«e±´X¸`¤¤ªºµ²ªG, §Ú̱N·|ÃÒ±o¦b
[x] ¤¤ªº irreducible element
©M prime element ¬O¤@¼Ëªº. ¥Ñ©ó
[x] ¨S¦³©Ò¦³ªº ideal ³£¬O
principle ideal ªº©Ê½è, §Ṳ́£¯à¥Î«e±ªº¤èªk¦pªkªw»s. §Ú̱N§Q¥Î
[x] ¤¤ªº irreducible element ªº©Ê½è¨ÓÀ°¦£³B²z,
©Ò¥H§ÚÌ»Ýn¥ý¤F¸Ñ¦b
[x] ¤¤ªº irreducible element ©M
[x]
¤¤ªº irreducible element ¤§¶¡ªºÃö«Y.
Lemma 7.3.11
Y
p(
x)
[
x],
deg(
p(
x)) > 0 ¥B
p(
x) ¬O¤@Ó primitive
polynomial, «h
p(
x) ¬O
[
x] ¤¤ªº irreducible element Y¥B°ßY
p(
x) ¬O
[
x] ¤¤ªº irreducible element.
µý ©ú.
º¥ý°²³]
p(
x) ¬O
[
x] ¤¤ªº irreducible element. ¦pªG
p(
x) ¦b
[
x] ¤¤¤£¬O irreducible element, ªí¥Ü¦s¦b
g(
x),
h(
x)
[
x]
º¡¨¬
0 < deg(
g(
x)) < deg(
p(
x)),
0 < deg(
h(
x)) < deg(
p(
x)) ¥B
p(
x) =
g(
x)
. h(
x). §Q¥Î Lemma
7.3.8 ª¾¦s¦b
m(
x),
n(
x)
[
x] ¥B
deg(
m(
x)) = deg(
g(
x)),
deg(
n(
x)) = deg(
h(
x)) º¡¨¬
p(
x) =
m(
x)
. n(
x). ¤]´N¬O»¡
m(
x)
¬O
p(
x) ªº divisor. ¦ý
0 < deg(
m(
x)) < deg(
p(
x)), ¬Gª¾
m(
x)
±1 ¥B
m(
x)
±
p(
x). ¦¹©M
p(
x) ¬O
[
x] ªº¤@Ó
irreducible element °²³]¬Û¥Ù¬Þ. ¬Gª¾
p(
x) ¤]¬O
[
x] ¤¤ªº
irreducible element.
¤Ï¤§, Y p(x) ¬O
[x] ¤¤ªº irreducible element. Y
p(x) = m(x) . n(x), ¨ä¤¤
m(x), n(x) [x]. ¥Ñ p(x) ¦b
[x] ¬O irreducible ªº°²³]ª¾ m(x) ©M n(x) ¤¤¦³¤@Ó¬O
[x] ªº unit, §Y±`¼Æ: ´N°²³] m(x) = d ¬O±`¼Æ§a! ¦]
m(x) [x] ¬Gª¾
d . ¥Ñ
p(x) = d . n(x) ª¾ d ¬O
p(x) ªº©Ò¦³«Y¼Æªº¤½¦]¼Æ. ¦ý¤wª¾ p(x) ¬O primitive, ¬G±o d = ±1. ¤]´N¬O»¡ p(x) ªº divisor ¥u¯à¬O ±1 ©M ±p(x)
³oºØ§Î¦¡, ¬G±o p(x) ¦b
[x] ¤¤¬O irreducible.
¥Ñ©ó
¬O¤@Ó field, ©Ò¥H¤W¤@¸`¤¤ F[x] ªº©Ê½è³£¥i®M¥Î¦b
[x] ¤W. §ÚÌn§Q¥Î
[x] ¤¤ªº irreducible ©M prime ¬O¤@¼Ëªº,
±o¨ì¦b
[x] ¤¤ªº irreducible ©M prime ¤]¬O¤@¼Ëªº.
Proposition 7.3.12
°²³]
p(
x)
[
x]. Y
p(
x) ¬O
[
x] ¤¤ªº irreducible
element, «h
p(
x) ¬O
[
x] ¤¤ªº prime element. ¤Ï¤§, Y
p(
x)
¬O
[
x] ¤¤ªº prime element, «h
p(
x) ¬O
[
x] ¤¤ªº
irreducible element.
µý ©ú.
º¥ýª`·N, ·í
deg(
p(
x)) = 0 ®Éªí¥Ü
p(
x)
¬O¤@Ó±`¼Æ.
§Ṳ́wª¾¦b
¤¤ªº irreducible ©M prime ¬O¤@¼Ëªº (Proposition
7.1.7), ©Ò¥H§ÚÌ¥unÃö¤ß
deg(
p(
x)) > 0 ªº±¡ªp.
º¥ý°²³] p(x) ¬O
[x] ¤¤ªº irreducible element. ¥Ñ Lemma
7.3.10 ª¾¨ä¬° primitive, ¬G¥Ñ Lemma 7.3.11 ª¾ p(x)
¤]¬O
[x] ¤¤ªº irreducible element. ¦A¥Ñ Proposition
7.2.11 ª¾ p(x) ¬O
[x] ¤¤ªº prime element. ²Y
f (x), g(x) [x] ¥B
p(x) | f (x) . g(x) in
[x], ¥Ñ
Lemma 7.3.7 ª¾
p(x) | f (x) . g(x) in
[x]. ¬G¥Ñ
p(x) ¦b
[x] ¬O prime ±o
p(x) | f (x) ©Î
p(x) | g(x) in
[x]. ¦A¥Ñ Lemma 7.3.7 ª¾
p(x) | f (x) ©Î
p(x) | g(x) in
[x]. ¤]´N¬O»¡ p(x) ¬O
[x] ¤¤ªº prime element.
¤Ï¤§, Y p(x) ¬O
[x] ¤¤ªº prime element. Y
p(x) = m(x) . n(x) ¨ä¤¤
m(x), n(x) [x]. «h¥Ñ©ó
p(x) | m(x) . n(x),
¥i±o
p(x) | n(x) ©Î
p(x) | m(x). Y
p(x) | n(x), §Y¦s¦b
(x) [x] ¨Ï±o
n(x) = (x) . p(x). ¬G±o
n(
x) =
(
x)
. n(
x)
. m(
x)
=
(
x)
. m(
x)
. n(
x).
¥Ñ
n(
x)
0 ¥H¤Î
[
x] ¬O integral domain, ±o
(
x)
. m(
x) = 1.
¤]´N¬O»¡
m(
x) ¬O
[
x] ªº unit, §Y
m(
x) = ±1. ¦P²z, Y
p(
x) |
m(
x) ¥i±o
n(
x) = ±1. ±oÃÒ
p(
x) ªº divisor ³£¬O ±1 ©M ±
p(
x) ³oºØ§Î¦¡, ¬Gª¾
p(
x) ¬O¤@Ó irreducible element.
²¦bnÃÒ©ú
[x] ¤Wªº°ß¤@¤À¸Ñ©Ê½èÅS¥X¤F¤@½uÀÆ¥ú,
«e±´X¸`¤¤§ÚÌÃÒ©ú°ß¤@¤À¸Ñ©Ê½è¨Ã¨S¦³¥Î¨ì¨C¤@Ó ideal ³£¬O principle
ideal ªº©Ê½è, ¦Ó¬O¥Î¨ì¦p Proposition 7.3.12 ¤¤¨CÓ irreducible
element ¬O prime ªº©Ê½è. ¦p¦P¦b¾ã¼Æªº±¡ªp, ¥Ñ©ó f (x) ©M - f (x)
ªº¤À¸Ñ¶È®t¤@Ó¥¿t¸¹, §ÚÌ¥i¥H¥u¦Ò¼³Ì°ª¦¸¶µ«Y¼Æ¬O¥¿¾ã¼Æªº
polynomial.
Theorem 7.3.13
Y
f (
x)
[
x] ¬O¤@Ó¤£¬° 0, 1, - 1 ¥B³Ì°ª¦¸¶µ«Y¼Æ¬O¥¿¾ã¼Æªº
polynomial, «h¦s¦b
p1(
x),...,
pr(
x)
[
x], ¨ä¤¤³o¨Ç
pi(
x)
¬O
[
x] ¤¤¨â¨â¬Û²§¥B³Ì°ª¦¸¶µ«Y¼Æ¬O¥¿¾ã¼Æªº irreducible elements,
º¡¨¬
f (
x) =
p1(
x)
n1 ... pr(
x)
nr,
ni ,
i {1,...,
r}.
¦pªG f (x) ¥i¥H¤À¸Ñ¦¨¥t¥ ªº§Î¦¡
f (x) = q1(x)m1 ... qs(x)ms, ¨ä¤¤³o¨Ç qi(x) ¤]¬O
[x]
¤¤¨â¨â¬Û²§¥B³Ì°ª¦¸«Y¼Æ¬O¥¿¾ã¼Æªº irreducible elements, «h r = s
¥B¸g¹LÅÜ´«¶¶§Ç¥i±o
pi(x) = qi(x), ni = mi,
i {1,..., r}.
µý ©ú.
º¥ýÃÒ©ú¦s¦b©Ê, ¤]´N¬O
f (
x) ¥i¼g¦¨¦³¦hÓ
[
x] ¤¤ªº
irreducible elements ªº¼¿n. §Ų̵́M (¹ï degree)
¥Î¼Æ¾ÇÂk¯Çªk¨ÓÃÒ©ú. °²³]
deg(
f (
x)) = 0, ¦]
f (
x)
¥B¤£¬O
unit, ¬G¥Ñ
ªº¤À¸Ñ©Ê½è (Theorem
7.1.8) ªº¦s¦b©Êª¾
f (
x)
¥i¼g¦¨¦³¦hÓ irreducible elements ªº¼¿n. ²°²³]¦s¦b©Ê¹ï degree
¤p©ó
n ªº polynomial ¬Ò¦¨¥ß. ·í
deg(
f (
x)) =
n ®É, Y
f (
x)
¥»¨¬O irreducible, ¦s¦b©Ê¦ÛµM¦¨¥ß. ¬G¶È³Ñ
f (
x) ¤£¬O irreducible
ªº±¡ªpn¦Ò¼. ¦¹®Énª`·N, ¦b
[
x] ¤¤¤@Ó polynomial ¬O
irreducible ¨Ã¤£ªí¥Ü¥L¤@©w¥i¥H¼g¦¨¨âÓ degree ¤ñ¸û¤pªº polynomials
ªº¼¿n (¨Ò¦p«e±´£¹Lªº¨Ò¤l 2
x + 2). ¦¹®É§ÚÌ¥ý±N
f (
x) ¼g¦¨
f (
x) =
c(
f )
. f*(
x), ¨ä¤¤
f*(
x)
[
x] ¬O primitive
polynomial. ¥Ñ©ó
c(
f )
, ¦A¤@¦¸§Q¥Î Theorem
7.1.8 ª¾
c(
f )= 1 ©Î¬O¥i¥H¼g¦¨¦³¦hÓ irreducible ±`¼Æ polynomials ªº¼¿n.
©Ò¥H§ÚÌ¥u³Ñ¤U¦Ò¼
f*(
x) ¬O§_¥i¼g¦¨¦³¦hÓ irreducible elements
ªº¼¿n. ·í
f*(
x) ¬O irreducible ®É, ¦s¦b©Ê¦ÛµM¤S¦¨¥ß¤F. ¦Ó·í
f*(
x) ¤£¬O irreducible ®É, Lemma
7.3.11 §i¶D§ÚÌ
f*(
x)
¦b
[
x] ¤£¬O irreducible, ¤]´N¬O
f*(
x) =
g(
x)
. h(
x) ¨ä¤¤
g(
x),
h(
x)
[
x] ¥B
0 < deg(
g(
x)) < deg(
f (
x)) ¥H¤Î
0 < deg(
h(
x)) < deg(
f (
x)). ¥Ñ Lemma
7.3.8 ª¾¦s¦b
m(
x),
n(
x)
[
x] ¥B
deg(
m(
x)) = deg(
g(
x)) ¥H¤Î
deg(
n(
x)) = deg(
h(
x)) ¨Ï±o
f*(
x) =
m(
x)
. n(
x). ¥Ñ©ó
deg(
m(
x)) < deg(
f (
x)) =
n ¥H¤Î
deg(
n(
x)) <
n, ¬G§Q¥ÎÂk¯Çªk°²³]ª¾
m(
x) ©M
n(
x) ³£¥i¼g¦¨¦³¦hÓ irreducible elements ªº¼¿n.
¦]¦¹±oÃÒ
f*(
x) ¥i¥H¼g¦¨¦³¦hÓ irreducible elements ªº¼¿n, ¬Gª¾
f (
x) =
c(
f )
f*(
x) ¤]¥i¼g¦¨¦³¦hÓ irreducible elements ªº¼¿n.
¦Ü©ó°ß¤@©Ê§Ų̵́M¥Î¼Æ¾ÇÂk¯Çªk¨Ó³B²z. Y
deg(f (x)) = 0, ¦]
f (x) , ¬G¥i¥H§Q¥Î Theorem 7.1.8 ªº°ß¤@©Ê±oÃҰߤ@©Ê.
²°²³]°ß¤@©Ê¹ï degree ¤p©ó n ªº polynomial ¬Ò¦¨¥ß. ·í
deg(f (x)) = n ®É, Y
f (x) = p1(x)n1 ... pr(x)nr = q1(x)m1 ... qs(x)ms,
¨ä¤¤
pi(
x)
¨â¨â¬Û²§,
qj(
x) ¤]¬O¨â¨â¬Û²§, ¦Ó¥B
pi(
x),
qj(
x) ³£¬O
[
x]
¤¤³Ì°ª¦¸¶µ«Y¼Æ¬O¥¿¾ã¼Æªº irreducible elements. ¥Ñ©ó
deg(
f (
x)) > 0,
¬Gª¾
pi(
x) ¤¤¥²¦s¦b¤@ polynomial ¨ä degree ¤j©ó 0,
¸g«±Æ«á§ÚÌ¥O¤§¬°
p1(
x). Proposition
7.3.12 §i¶D§ÚÌ
p1(
x) ¬O
[
x] ªº prime element, ¬G¥Ñ
p1(
x) |
f (
x) ±oª¾,
qj(
x) ¤¤¦³¤@ polynomial ·|³Q
p1(
x) ¾ã°£, ¸g«±Æ«á§ÚÌ¥O¤§¬°
q1(
x). ¤]´N¬O»¡
p1(
x) |
q1(
x). µM¦Ó
q1(
x) ¬O
irreducible, ¨ä divisor ¥u¦³ ±1 ©M
±
q1(
x). ¤S¦]¤wª¾
deg(
p1(
x)) > 0 ¥B
p1(
x) ©M
q1(
x) ªº³Ì°ª¦¸¶µ«Y¼Æ³£¬O¥¿¾ã¼Æ,
¬G±o
p1(
x) =
q1(
x). ¦]¦¹§ÚÌ¥i±N
f (
x) ªº¤À¸Ñ§ï¼g¦¨
f (x) = p1(x)n1 . p2(x)n2 ... pr(x)nr = p1(x)m1 . q2(x)m2 ... qs(x)ms.
±N¤W¦¡²¾¶µ¦A´£¥X
p1(
x), §ÚÌ¥i±o
p1(
x)
. p1(
x)
n1 - 1 . p2(
x)
n2 ... pr(
x)
nr -
p1(
x)
m1 - 1 . q2(
x)
m2 ... qs(
x)
ms = 0.
¥Ñ©ó
p1(
x)
0 ¥B
[
x] ¬O integral
domain, §Ú̱o
p1(x)n1 - 1 . p2(x)n2 ... pr(x)nr - p1(x)m1 - 1 . q2(x)m2 ... qs(x)ms = 0.
²¥O
g(
x) =
p1(
x)
n1 - 1 . p2(
x)
n2 ... pr(
x)
nr. ¥Ñ©ó·íªì¿ï¨ú
p1(
x) º¡¨¬
deg(
p1(
x)) > 0, ¬G±o
deg(g(x)) = deg(f (x)) - deg(p1(x)) < deg(f (x)) = n
¥B
g(x) = p1(x)n1 - 1 . p2(x)n2 ... pr(x)nr = p1(x)m1 - 1 . q2(x)m2 ... qs(x)ms
¬O
g(
x) ªº¨âÓ¤À¸Ñ, ¬G§Q¥ÎÂk¯Çªk°²³]§Ú̦³
r =
s ¥B
p1(
x) =
q1(
x),...,
pr(
x) =
qr(
x) ¥H¤Î
n1 =
m1,
n2 =
m2,...,
nr =
mr, ¬G±oÃҰߤ@©Ê.
¥Ñ Theorem 7.3.13 ª¾
[x] ¤¤ªº irreducible elements ´N¦p¦P
¤¤ªº½è¼Æ¤@¼Ë«n. ¥t¤@¤è±§Q¥Î Lemma 7.3.8 ¤]§i¶D§Ú̦b
[x] ¤¤ªº irreducible element ¦b
[x] ¤¤¤]¬O irreducible.
¦]¦¹±´°Q
[x] ¤¤¦³þ¨Ç irreducible elements ¬O¤@Ó«nªº½ÒÃD.
¨ä¹êµ¹©w
f (x) [x] n§PÂ_¨ä¬O§_¬° irreducible ¨Ã¤£®e©ö.
¥H¤U§Ṳ́¶²Ð¤@ºØ¤èªk¥i¥H½T»¬Y¤@Ãþªº polynomial ¬O irreducible.
Proposition 7.3.14 (Eisenstein Criterion)
¥O
f (
x) =
xn +
an - 1xn - 1 +
... +
a1x +
a0 [
x],
¨ä¤¤
n > 0.
°²³]¦s¦b¤@½è¼Æ
p º¡¨¬
p |
a0,
p |
a1, ...,
p |
an - 1 ¦ý
p2a0,
«h
f (
x) ¬O
[
x] ¤¤ªº irreducible element.
µý ©ú.
¥Ñ©ó
c(
f )= 1 ©Ò¥H
f (
x) ¬O primitive polynomial. ¦]¦¹n»¡©ú
f (
x)
¬O irreducible in
[
x] ¥un»¡©ú
f (
x) ¤£¥i¯à¼g¦¨¨âÓ degree
¤p©ó
n ªº polynomials ªº¼¿n. §Ú̧Q¥Î¤ÏÃÒªk¨ÓÃÒ©ú.
°²³]
f (x) = g(x) . h(x) ¨ä¤¤
g(
x) =
crxr +
... +
c1x +
c0 [
x], 0 <
r <
n
¥B
h(
x) =
dsxs +
... +
d1x +
d0 [
x], 0 <
s <
n.
¦Ò¼
g(
x)
. h(
x) ªº±`¼Æ¶µ
c0 . d0 =
a0. ¥Ñ°²³]
p |
a0 =
c0 . d0, ¬Gª¾
p |
c0 ©Î
p |
d0. µM¦Ó¤Sª¾
p2c0 . d0, ¬Gª¾
c0 ©M
d0 ¶¡¥u¯à¦³¤@Ó³Q
p
¾ã°£. §ÚÌ´N°²³]¬O
c0 §a! ¤]´N¬O»¡
p |
c0 ¦ý
pd0. ²¦bÆ[¹î
g(
x)
. h(
x) ªº¤@¦¸¶µ«Y¼Æ
c0 . d1 +
c1 . d0 =
a1. ¥Ñ°²³]
p |
a1 ¥H¤Îè¤ ±oª¾ªº
p |
c0 ¥i±o
p |
c1 . d0. ¦ý¤Sª¾
pd0 ¬G±o
p |
c1.
³o¼Ë¤@ª½¤U¥h§ÚÌ·Q¥Î¼Æ¾ÇÂk¯ÇªkÃÒ±o
p |
cr. ¤]´N¬O°²³]¤wª¾
p |
c0,
p |
c1,...,
p |
cr - 1, §Ú̱ýÃÒ±o
p |
cr.
²¦Ò¼
g(
x)
. h(
x) ªº
xr ¶µ«Y¼Æ
c0 . dr + c1 . dr - 1 + ... + cr - 1 . d1 + cr . d0 = ar.
(³oÓ¦¡¤l¸ÌY
s <
r, ¨º·íµM¬O¥O
ds + 1 =
... =
dr = 0) ¥Ñ©ó 0 <
r <
n ¬Gª¾
p |
ar, ¦A¥[¤WÂk¯Ç°²³]
p |
c0,...,
p |
cr - 1, §ÚÌ¥i±o
p |
cr . d0. §O§Ñ¤F
pd0, ¬G±oÃÒ
p |
cr.
²¦b§Ú̦Ҽ
g(
x)
. h(
x) ªº³Ì°ª¦¸¶µ«Y¼Æ (§Y
f (
x) ªº
xn
¶µ«Y¼Æ)
cr . ds = 1.
¤j®a°¨¤W¬Ý¥X¥Ñ
p |
cr ¤£¥i¯à±o¨ì
cr . ds = 1.
¦]¦¹±o¨ì¥Ù¬Þ, ¤]´N¬O»¡
f (
x) ¬O
[
x] ªº irreducible element.
³Ì«á§ÚÌ«¥Ó¤@¤U, ¥Ñ Lemma 7.3.8 (©Î Lemma 7.3.11)
§Ú̪¾¹D²Å¦X Proposition 7.3.14 ªº polynomials ¦b
[x] ¤]¬O
irreducible.
¤U¤@¶: Quotient Field of an
¤W¤@¶: ¤@¨Ç±`¨£ªº Rings
«e¤@¶: Ring of Polynomials over
Administrator
2005-06-18