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adj A = A^(n1), even if A=0 or a zerodivisor
Posted:
May 2, 1999 5:54 PM


Let A be an n by n matrix over a commutative ring.
n1 Show A~ = A , A~ = adjoint A, A = det A
T Note: since A A~ = A I, taking determinants
n yields A A~ = A
but A can't be "naively" canceled if it is 0 (or a zerodivisor).
Hint: see the next page.
Bill Dubuque
Hint: free your mind to think universally.



