Answer by Berci for For each of the following formulae ϕ(x), show why the set...
Your ideas seem not aiming the original intention of the question.Hint: Each of the given formulas is either valid for all $x$ or is false for all $x$.We get $\{x:\Phi(x)\}$ as a set only in the latter...
View ArticleFor each of the following formulae ϕ(x), show why the set {x : ϕ(x)} does or...
For each of the following formulae ϕ(x), show why the set {x : ϕ(x)} does or does not exist:(i) ∀y (x ∈ y). My thinking here is that the empty set is a subset of all sets(ii) ∃y (x ∈ y). My thinking...
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