Gea-Suan Lin’s technical note and murmuring :)
Posted in Mathematics at 3:54 am by gslin
鋼管在 IRC 上問了一個線代問題：I-AB 可逆，證 I-BA 可逆。
其實解法很簡單，用 Google 找 “I-AB” “I-BA”，第二個就是答案了 :p
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zhangqisen Said:
July 29, 2005 at 11:15 pm
用反正法，若I-BA不可逆，则︱Ｉ－ＢＡ︱＝．．．＝︱I-AB︱＝０，矛盾．故可逆．
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zhangqisen Said:
July 29, 2005 at 11:15 pm
用反正法，若I-BA不可逆，则︱Ｉ－ＢＡ︱＝．．．＝︱I-AB︱＝０，矛盾．故可逆．