Differences
This shows you the differences between two versions of the page.
Both sides previous revision Previous revision Next revision | Previous revision Next revision Both sides next revision | ||
sav08:forward_vcg [2009/03/10 20:46] vkuncak |
sav08:forward_vcg [2010/03/09 17:18] vkuncak |
||
---|---|---|---|
Line 84: | Line 84: | ||
sp(\{s.\ P\}, r_c(c_1)) = \{ s.\ sp_F(P,c_1) \} | sp(\{s.\ P\}, r_c(c_1)) = \{ s.\ sp_F(P,c_1) \} | ||
\] | \] | ||
+ | |||
+ | |||
+ | |||
===== Example ===== | ===== Example ===== | ||
- | Let's take a small example with precondition: $\{x \ge 5 \wedge y \ge 3\}$ and code: | + | Precondition: $\{x \ge 5 \wedge y \ge 3\}$. Code: |
<code> | <code> | ||
- | x = x + y+10; | + | x = x + y + 10 |
</code> | </code> | ||
\[ | \[ | ||
- | sp(x \ge 5 \land y \ge 3, x=x+1) = \exists x_0.\ x_0 \ge 5 \wedge y \ge 3\ \land\ x = x_0 + y | + | \begin{array}{l} |
+ | sp(x \ge 5 \land y \ge 3, x=x+y+10) = \\ | ||
+ | \exists x_0.\ x_0 \ge 5 \wedge y \ge 3\ \land\ x = x_0 + y + 10 \\ | ||
+ | \leftrightarrow \ y \ge 3 \land x \ge y + 15 | ||
+ | \end{array} | ||
\] | \] | ||