Timeline for Show that if L is regular, then third(L) is also regular. Hint: Construct an ϵ-NFA from the DFA for L

11 events

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Jun 16, 2020 at 10:30	history	edited	CommunityBot		Commonmark migration
Dec 7, 2018 at 23:37	history	edited	Alfred Kaminski	CC BY-SA 4.0	I added a new (comparatively-minor) question.
Dec 7, 2018 at 23:33	comment	added	Alfred Kaminski		Thank you both (regarding this series of comments). :)
Dec 6, 2018 at 18:58	answer	added	Hendrik Jan		timeline score: 1
Dec 6, 2018 at 15:51	answer	added	Uli Schlachter		timeline score: 2
Dec 6, 2018 at 15:32	comment	added	Uli Schlachter		In the third line of the transition relation, if you replace $\langle q,4\rangle$ with $\langle q,1\rangle$ in $(\langle p,3\rangle,a,\langle q,4\rangle)$, then you no longer need the fourth copy of $A$. Also, the initial state should be $\langle s_0,1\rangle$.
Dec 6, 2018 at 3:16	comment	added	Yuval Filmus		You ask whether $(p,a,q) \in \delta$ is the same as $\delta(p,a) = q$. It isn't since for an NFA, $\delta(p,a)$ is a set of states rather than a single state.
Dec 6, 2018 at 3:15	comment	added	Yuval Filmus		I'm not sure why we need four copies – it seems that three should be enough. Perhaps you also need an additional initial state to handle $\epsilon$.
Dec 6, 2018 at 3:14	comment	added	Yuval Filmus		The solution is indeed missing an initial state.
Dec 6, 2018 at 3:14	history	edited	Yuval Filmus	CC BY-SA 4.0	added 7 characters in body
Dec 5, 2018 at 23:07	history	asked	Alfred Kaminski	CC BY-SA 4.0