Hi I'm learning first order logic, and would like to prove that $\Gamma\vdash(\psi_1\lor\psi_2)$ is equivalent to $\Gamma\vdash\psi_1$ or $\Gamma\vdash\psi_2$ using logic axiom of the following:
- $((\phi_1\to(\phi_2\to\phi_3))\to((\phi_1\to\phi_2)\to(\phi_1\to\phi_3)))$
- $(\phi_1\to\phi_1)$
- $(\phi_1\to(\phi_2\to\phi_1))$
- $(\phi_1\to((\lnot\phi_1)\to\phi_2))$
- $(((\lnot\phi_1)\to\phi_1)\to\phi_1)$
- $((\lnot\phi_1)\to(\phi_1\to\phi_2))$
- $(\phi_1\to((\lnot\phi_2)\to(\lnot(\phi_1\to\phi_2))))$
The equivalent expression for $(\psi_1\lor\psi_2)$ is $((\lnot\psi_1)\to\psi_2)$
Thanks a lot!!!