Does every set admit a complement to form a direct sum as: $X=A\oplus A'$
I don't think so and my first guess would be: $X:= \mathbb R$, $A:= \lbrace -1,0,+1\rbrace$
Can somebody proof this? Or give another counterexample? Thx, Alex
2026-03-30 08:36:03.1774859763
Direct Sum: Complement
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