Question

if Y is a subset of x​

Answer 1

Answer:

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Answer 2

Step-by-step explanation:

If Y is a subspace of X, we say that a set U is open in Y if U ∈ TY ; this implies in particular that it is a subset of Y . We say that U is open in X if U ∈ TX. ... Since U is open in Y , U = Y ∩ V for some set V open in X. Since Y and V are both open in X, so is Y ∩ V .