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It's an FOL proof It's an FOL proof (you can take a look here) Thank you so much!

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On line 3 you should assume $F(a)$

Remember you are setting up an $\exists$ Elim on $\exists x \ F(x)$ (Indeed, line 7 should refer to premise 2, not 1) and so you should take the formula $F(x)$ and substitute a constant for the $x$.

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  • $\begingroup$ Hi Bram28! I took your advice about F(a) but I'm still not sure how to finish off the proof $\endgroup$
    – notMW
    Dec 5, 2019 at 23:09
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    $\begingroup$ @user726371 Note that after assuming Fa, you can simply infer Fa v Ga using v Intro $\endgroup$
    – Bram28
    Dec 6, 2019 at 2:49

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