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The state-transition diagram of a finite-state recogniser is as follows :

enter image description here

HS'
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  • What do the undirected edges mean? – AlexR May 19 '15 at 15:28
  • @AlexR - I'm unsure. I'm working off a practice paper and this is as displayed on one of the questions. I would assume the edges are supposed to be directed on the path towards the acceptance state. – HS' May 19 '15 at 15:31
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    Okay, in that case my answer is correct. – AlexR May 19 '15 at 15:32

1 Answers1

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I assume the undirected edges are meant left-to-right ($\to$).

Start with $s_0$ and repeat as many $a$ and $c$ as you want, then transition with $b$: [ac]*b. Then we need a $d$,$a$ and optionally any number of occurrences of $b$,$d$,$a$, i.e. [ac]*bda(bda)* Or shorter

[ac]*(bda)+
AlexR
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