Valid Formula
# Definition
Let $\mathcal{L}$ be a Language. $\phi$ is a Valid $\mathcal{L}$-Formula if for each $\mathcal{L}$-structure $\mathcal{M}$ and each Assignment $\sigma$, we have that $\mathcal{M} \models_{\sigma} \phi$.
Search
Let $\mathcal{L}$ be a Language. $\phi$ is a Valid $\mathcal{L}$-Formula if for each $\mathcal{L}$-structure $\mathcal{M}$ and each Assignment $\sigma$, we have that $\mathcal{M} \models_{\sigma} \phi$.