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Is there a way to see whether a topological space $\Omega$ does not allow retractions $r: \Omega \mapsto B$, with $B$an arbitrarya given subspace of $\Omega$ ?
In other words: when is a space not retractable to a given subspace $B$ ?
Is there a way to see whether a topological space $\Omega$ does not allow retractions $r: \Omega \mapsto B$, with $B$an arbitrary subspace of $\Omega$ ?
In other words: when is a space not retractable ?
Is there a way to see whether a topological space $\Omega$ does not allow retractions $r: \Omega \mapsto B$, with $B$a given subspace of $\Omega$ ?
In other words: when is a space not retractable to a given subspace $B$ ?
Is there a way to see whether a topological space $\Omega$ does not allow retractions $r: \Omega \mapsto B$, with $B$ an arbitrary subspace of $\Omega$ ?
