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Timestamp:
Apr 10, 2012, 4:30:02 PM (13 years ago)
Author:
syed
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/papers/FDL2012/

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  • papers/FDL2012/abstraction_refinement.tex

    r92 r93  
    2424
    2525Refinements based on the concretization of selected abstract variables in
    26 $\widehat{M}_i$ ensure item 2. Concretization can be performed either in
    27 modifying the AKS of $\widehat{M}_i$, by changing some abstract value to
    28 concrete ones, but this approach is rude : in order to ensure item 1,
    29 concretization needs to be consistent with the sequences of values in the concrete system. The difficulty resides in defining the proper abstract variable to concretize, at which precise instant, and with which Boolean value.
     26$\widehat{M}_i$ ensure item 2. Concretization can be performed by
     27modifying the AKS of $\widehat{M}_i$ by changing some abstract value to
     28concrete ones. However, this approach is rude : in order to ensure item 1,
     29the concretization needs to be consistent with the sequences of values in the concrete system. The difficulty resides in defining the proper abstract variable to concretize, at which precise instant, and with which Boolean value.
    3030%Another way to concretize some variables at selected instants is to compose
    3131%(by a synchronous product) the AKS  of $\widehat{M}_i$ with a new AKS, provided this latest represents over-approximations of the set of behaviors of $M$. By construction, this product satisfies items 1 and 2. We now have to compute an AKS eliminating the spurious counterexample, being easily computable and ensuring a quick convergence of the CEGAR loop.
     
    9696\end{itemize}
    9797\end{definition}
    98 The labeling function fo $s_i'$ represents (concrete) configuration of state $s_i$ and state $\bar{s_i}$  represents all
     98The labeling function of $s_i'$ represents (concrete) configuration of state $s_i$ and state $\bar{s_i}$  represents all
    9999configurations {\it but} the one of $s_i$. This last set may not be representable by
    100100the labeling function defined in def \ref{def-aks}. State labeling is treated
     
    114114and assigns to each of them a label of $k$ variables $\{v_0, \ldots,
    115115v_{k-1}\}$ defined such that : $\widehat{L}(\bar{s_i^j}) = \{\forall l \in [0..k-1],
    116 v_l = \neg  {L}_{i}(s_i)[v_l], \forall l \in [j+1..k-1], v_l = \top\}$. each
     116v_l = \neg  {L}_{i}(s_i)[v_l], \forall l \in [j+1..k-1], v_l = \top\}$. Each
    117117state $\bar{s_i^j}$ is connected to the same predecessor and successor states
    118118as state $\bar{s_i}$.
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