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Inductively Finding a Reachable State Space Over-Approximation. EE 290a Project Presentation Mike Case. Sequential Optimization. One optimization approach:. State space. Reachable state space. Can be used as don’t cares. Requires state reachability analysis Prohibitively expensive
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Inductively Finding a Reachable State Space Over-Approximation EE 290a Project Presentation Mike Case
Sequential Optimization • One optimization approach: State space Reachable state space Can be used as don’t cares • Requires state reachability analysis • Prohibitively expensive • Can be approximated Mike Case
Van Eijk’s Method • Uses induction rather than reachability analysis • Fast but incomplete • Finds sequentially equivalent nodes in a network • Nodes are identical in every reachable state • States where equivalences hold is an over-approximation of the reachable states Mike Case
Van Eijk’s Inductive Hypothesis • Base Case: • A set of node equivalences holds for the initial state • Inductive Hypothesis: • If equivalences hold in one state then they hold in every 1-reachable state as well Mike Case
Van Eijk Weaknesses • Originally for equivalence checking • Doesn’t find many sequential equivalences in optimization Mike Case
Generalizing Van Eijk • Find implications rather than exact equivalences • Implications subsume equivalences • (A B) (B A) (A = B) Mike Case
Implication Inductive Hypothesis • Base Case: • A set of node implication holds for the initial state • Inductive Hypothesis: • If implications hold in one state then they hold in every 1-reachable state as well • Exactly like Van Eijk! Mike Case
State Reachability • Induction gaurantees: • In every reachable state, implications hold State space States where implications hold Reachable state space Mike Case
Sequential-Only Implications • Combinational implications: • True for every state • Tell us nothing • Sequential implications: • True for every reachable state • Gives reachable state space approximation Mike Case
Implementation Overview • Implemented in MVSIS • Used and-inverter graphs and SAT Mike Case
= 1? Base Case Mike Case
InductiveStep Mike Case
Results - Performance Mike Case
Results – State Space DCs Mike Case
Results - Synthesis Mike Case