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sav07_lecture_3_skeleton [2007/03/20 18:21] wikiadmin |
sav07_lecture_3_skeleton [2007/03/20 21:13] vkuncak |
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===== Converting programs (with simple values) to formulas ===== | ===== Converting programs (with simple values) to formulas ===== | ||
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* represent programs using guarded command language, e.g. desugaring of 'if' into non-deterministic choice and assume | * represent programs using guarded command language, e.g. desugaring of 'if' into non-deterministic choice and assume | ||
* give meaning to guarded command language statements as relations | * give meaning to guarded command language statements as relations | ||
- | * we can represent relations using set comprehensions; if our program c has two state components, we can represent its meaning R( c ) as | + | * we can represent relations using set comprehensions; if our program c has two state components, we can represent its meaning R( c ) as $\{((x_0,y_0),(x,y)) \mid F \}$, where F is some formula that has x,y,x_0,y_0 as free variables. |
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- | $\{((x_0,y_0),(x,y)) \mid F \}$ | + | |
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- | , where F is some formula that has x,y,x_0,y_0 as free variables. | + | |
* this is what I mean by ''simple values'': later we will talk about modeling pointers and arrays, but we will still use this as a starting point. | * this is what I mean by ''simple values'': later we will talk about modeling pointers and arrays, but we will still use this as a starting point. | ||
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What exactly do we prove about the formula R( c ) ? | What exactly do we prove about the formula R( c ) ? | ||
- | We prove that this formula is **valid** | + | We prove that this formula is **valid**: |
R( c ) -> error=false | R( c ) -> error=false | ||
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- | Test : \\ | ||
- | \begin{eqnarray*} | ||
- | \Psi_0 &=& -C_{abcd} Y_0^a m^b Y_1^c m^d e^{-2i\gamma} \\ | ||
- | \Psi_4 &=& -C_{abcd} Y_1^a \bar{m}^b Y_1^c \bar{m}^d e^{2i\gamma} | ||
- | \end{eqnarray*} |