¤U¤@¶: ±N ring ¬Ý¦¨¬O vector
¤W¤@¶: ½u©Ê¥N¼ÆªºÀ³¥Î
«e¤@¶: ½u©Ê¥N¼ÆªºÀ³¥Î
¦b³o¸Ì§Ú̶Ȳ³æ¦^ÅU¤°»ò¬O vector
space, basis ¥H¤Î dimension. §Ṳ́£µ¹³o¨Ç°ò¥»©Ê½èªºµý©ú,
Y¤£²M·¡ªº¦P¾Ç½Ð°Ñ¦Ò¤@¯ë¦³Ãö½u©Ê¥N¼Æªº®ÑÄy.
Definition 9.3.1
¥O
F ¬O¤@Ó field. §ÚÌ»¡
V ¬O¤@Ó
vector space over F,
¦pªG
V ¥»¨¤¸¯À¶¡¦³¥[ªk ``+'' ¹Bºâ, ¦Ó¥B¹ï¥ô·N
c F,
v V
¬Ò¦³
c . v V, ¥Bº¡¨¬:
- (VS1)
- V ¦b¥[ªk¤§¤U¬O¤@Ó abelian group.
- (VS2)
- ¹ï©Ò¦³ªº c F ¥H¤Î
v1, v2 V ¬Ò¦³
c . (v1 + v2) = c . v1 + c . v2.
- (VS3)
- ¹ï©Ò¦³
c1, c2 F ¥H¤Î v V ¬Ò¦³
(c1 + c2) . v = c1 . v + c2 . v ¥B
c1 . (c2 . v) = (c1 . c2) . v.
- (VS4)
- ¹ï¥ô·N v V ¬Ò¦³
1 . v = v, ¨ä¤¤ 1 F ¬O
F ¼ªkªº identity.
³o¸Ìnª`·N¤@¯ë vector space ªº©w¸q¸Ì¨Ã¨S¦³n¨D
F V,
¤]¨S¦³n¨D V ªº¤¸¯À¶¡¦³¼ªk¹Bºâ. ¤£¹L±N¨Ó§ÚÌ°Q½× field
ªº©Ê½è®É©Ò¸I¨ìªº vector space ³£·|ÃB¥ ¦³
F V ¥H¤Î V
ªº¤¸¯À¶¡¦³¼ªk¹Bºâ³o¨âºØ¯S©Ê. ¤]´N¬O³o¨âºØ¯S©Ê¨Ï±o field
ªº©Ê½è¤ñ¤@¯ëªº vector space ±j±o¦h.
Definition 9.3.2
°²³]
F ¬O¤@Ó field ¥B
V ¬O¤@Ó vector space over
F, ¦pªG
v1,...,
vn V º¡¨¬¹ï¥ô·N
v F ¬Ò¦s¦b
c1,...,
cn F
¨Ï±o
v = c1 . v1 + ... + cn . vn,
«hºÙ
v1,...,
vn
span V over
F.
¦pªG¤@Ó vector space ¦s¦b¤@²Õ
v1,..., vn V span V over
F, «h§Ú̺٠V ¬O¤@Ó finite dimensional vector space over
F.
¦pªG
v1,..., vn span V over F, ·íµM¤]¦³¥i¯à¦³¥t¤@²Õ
w1,..., wm V ¤] span V over F.
§ÚÌ·íµM§Æ±æ¯à§ä¨ì¤@²Õ¤¸¯À³Ì¤Öªº
v1,..., vn ¥i¥H span V over
F. n¹F¨ì³o¤@ÂI
v1,..., vn ¤§¶¡¦Ü¤Ön¨S¦³½u©ÊÃö«Y,
n¤£µM¨ä¤¤ªº¬YÓ vi ¥i¥H³Q¨ä¥Lªº vj ®i¦¨,
§ÚÌ´N¥i¥H§ä¨ì§ó¤Öªº¤¸¯À span V ¤F. ¦]¦¹§Ú̦³¥H¤Uªº©w¸q.
Definition 9.3.3
°²³]
F ¬O¤@Ó field ¥B
V ¬O¤@Ó vector space over
F, ¦pªG¹ï©ó
V ¤¤ªº¤@²Õ¤¸¯À
v1,...,
vn V §Ú̳£§ä¤£¨ì¤£¥þ¬° 0 ªº
c1,...,
cn F ¨Ï±o
c1 . v1 + ... + cn . vn = 0,
«hºÙ³o²Õ
v1,...,
vn ¬O
linearly independent over
F.
¦pªG
v1,..., vn F span V ¥B¬O linearly independent over
F, «hºÙ
v1,..., vn ¬O¤@²Õ basis of V over F.
½u©Ê¥N¼Æ¤¤³Ì°ò¥»ªº©Ê½è´N¬O·í V ¬O finite dimensional vector space
over F ®É, ¤@©w¥i¥H§ä¨ì V over F ªº¤@²Õ basis. ÁöµM
basis ¨Ã¤£¬O°ß¤@ªº, ¤£¹L¥ô¤@²Õ basis ¨ä¤¸¯ÀӼƳ£¬O¬Û¦Pªº. ³oÓ
basis ªºÓ¼ÆºÙ¤§¬° V over F ªº dimension, §ÚÌ°O¬°
dimF(V). ¤]´N¬O»¡Y
dimF(V) = n, «h¥i¥H§ä¨ì¤@²Õ
v1,..., vn V ¬O linearly independent over F ¥B span V
over F.
¦pªG
W V ¥B§Q¥Î V ©M F ¶¡ªº¹Bºâ W ¤]¬O¤@Ó vector
space over F, «hºÙ W ¬O V ªº¤@Ó subspace over F.
¥H¤U¬O dimension ¤@¨Ç°ò¥»ªº©Ê½è, §Ú̲¤¥hÃÒ©ú.
Lemma 9.3.4
°²³]
F ¬O¤@Ó field ¥B
V ¬O¤@Ó finite dimensional vector space
over
F.
- Y
v1,..., vn span V over F, «h
dimF(V)n.
- Y
w1,..., wm F ¬O linearly independent over F, «h
dimF(V)m.
- Y W ¬O V ªº¤@Ó subspace over F, «h
dimF(V)dimF(W).
¤U¤@¶: ±N ring ¬Ý¦¨¬O vector
¤W¤@¶: ½u©Ê¥N¼ÆªºÀ³¥Î
«e¤@¶: ½u©Ê¥N¼ÆªºÀ³¥Î
Administrator
2005-06-18