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Implementation of State Elimination Using

HeuristicsAuthor: Jae-Hee Ahn, Yo-Sub HanPublisher: CIAA 2009Presenter: Li-Hsien, HsuData: 5/9/2012

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Introduction

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Introduction

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Introduction

The size of a regular expression from state elimination depends on the state removal sequence.

2 -> 4

4 -> 2

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Heuristics for State EliminationThe Decomposition Heuristic

vertical decomposition horizontal decomposition

The State Weight Heuristic

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Vertical DecompositionDefinition 1. We define a state q in an FA A to be a bridge

state if it satisfies the following conditions:1. State q is neither a start nor a final state.2. For each string w ∈ L(A), its path in A must pass through q at least once.3. State q is not in any cycle except for the self-loop.

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Vertical Decomposition

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Horizontal DecompositionFor horizontal chopping of a given FA A = (Q,Σ, δ, s, f), we

have to identify subautomata of A such that all subautomata are disjoint from each other except s and f.

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The State Weight Heuristic

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The State Weight Heuristic

(1*2)+(1*1+1*1)+5*(1*2) = 14

Out = 2

In = 1

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C-IEliminate states in order. C-IIUsing VC & HC, and eliminateStates in order. C-IIIUsing SWH only once. C-IVUsing VC & HC, and eliminateStates with SWH only once. C-VUsing SWH in every steps. C-VIUsing VC & HC, and eliminateStates with SWH in every steps.

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