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return to viewing 'Borel space'
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2009-01-24 01:12:45
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Version 11 --> Version 12
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bci1
A \emph{rigid Borel space} $(X_r; \mathcal{B} (X_r))$ is defined as a Borel space whose only automorphism
$f: X_r \to X_r$ (that is, with $f$ being a bijection, and also with $f(A) = f^{-1}(A)$ for any $A \in \mathcal{B}(X_r)$) is the identity function $1_{X_r; \mathcal{B} (X_r))}$.
R. M. Shortt and J. Van Mill provided the first construction of a rigid Borel space on a `set of large cardinality'
(that is, on a class). |
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