Answer by Imperishable Night for A question about the axiom schema of separation
but I wonder why would someone use this an instance of this axiom schema, while letting the variable $y$ to be free in $\phi$.There are some situations where it is obviously more convenient to use an...
View ArticleAnswer by spaceisdarkgreen for A question about the axiom schema of separation
I believe that the reason that we do not allow $x$ to be a freevariable in the formula $\phi$ is because otherwise we would bedefining the set $x$ in terms of the set $x$ (informally, it happensself...
View ArticleA question about the axiom schema of separation
I am currently studying axiomatic set theory and I am struggle to answer some questions regarding the axiom schema of separation. First, let me introduce some context. It is usual to state the axiom...
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