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Notes/MFES/T - Aula 2 - 18 Setembro 2023.md

@@ -67,16 +67,16 @@ A formula $F$ is:
    >  - $\Gamma \models G$ and $\Gamma$ finite iff $\models \land \Gamma \implies G$.
    >  
 
- - Let $\Gamma = { F_1, F_2, F_3,... }$ be a set of formulas.
 	 - $\Gamma$ is *consistent* or *satisfiable* iff there is an assignment that models $\Gamma$.
 	 - We say that $\Gamma$ is inconsistent or unsatisfiable iff there is not consistent and denote this by $\Gamma \models \bot$.
 
    > [!tip]+ Proposition
-   >  - {$F, \neg F$} \$models \bot$
+   >  - {$F, \neg F$} $\models \bot$
    >  - If $\Gamma \models \bot$ and $\Gamma \subseteq \Gamma '$, then $\Gamma ' \models \bot$
    >  - $\Gamma \models F$ iff $\Gamma, \neg F \models \bot$
 
-- Formula
+- Formula $G$ is a subformula of formula F if it occurs syntactically within F
+- Formula G is a strict subformula of F if G is a subformula of $F$ and $G \neg \equals F$
    
 ### 1.2.1 Basic Equivalences 
 1. $\neg \neg A \equiv A$