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sav08:homework05 [2008/03/25 14:24] piskac |
sav08:homework05 [2015/04/21 17:30] (current) |
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**Part c)** Prove (using appropriate proof technique) that your definition of fsfsubst has the property | **Part c)** Prove (using appropriate proof technique) that your definition of fsfsubst has the property | ||
- | \[ | + | \begin{equation*} |
e_F(fsfsubst(\{x_1 \mapsto t_1,\ldots,x_n \mapsto t_n\})(F))(I) = e_F(F)(I[x_1 \mapsto e_T(t_1)(I),\ldots, x_n \mapsto e_T(t_n)(I)]) | e_F(fsfsubst(\{x_1 \mapsto t_1,\ldots,x_n \mapsto t_n\})(F))(I) = e_F(F)(I[x_1 \mapsto e_T(t_1)(I),\ldots, x_n \mapsto e_T(t_n)(I)]) | ||
- | \] | + | \end{equation*} |
You can assume that formulas are built using only these symbols: | You can assume that formulas are built using only these symbols: | ||
* one constant $a$ | * one constant $a$ | ||
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Consider the definition of [[First-Order Logic Semantics#Consequence set]] defined in [[First-Order Logic Semantics]]. | Consider the definition of [[First-Order Logic Semantics#Consequence set]] defined in [[First-Order Logic Semantics]]. | ||
Prove that it satisfies these properties where $T_1$, $T_2$ denote sets of formulas. | Prove that it satisfies these properties where $T_1$, $T_2$ denote sets of formulas. | ||
- | \[ | + | \begin{equation*} |
\begin{array}{rcl} | \begin{array}{rcl} | ||
T &\subseteq & Conseq(T) \\ | T &\subseteq & Conseq(T) \\ | ||
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T_1 \subseteq Conseq(T_2) \land T_2 \subseteq Conseq(T_1) & \rightarrow & Conseq(T_1) = Conseq(T_2) | T_1 \subseteq Conseq(T_2) \land T_2 \subseteq Conseq(T_1) & \rightarrow & Conseq(T_1) = Conseq(T_2) | ||
\end{array} | \end{array} | ||
- | \] | + | \end{equation*} |
===== Problem 4 (Optional) ===== | ===== Problem 4 (Optional) ===== |