Timeline for How can the union of two 'context-free but not regular' languages be regular?
Current License: CC BY-SA 4.0
4 events
| when toggle format | what | by | license | comment | |
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| Jul 25, 2019 at 21:06 | comment | added | John L. | Here is another general construction. Let $\Sigma=\{a,b\}$. Let $L$ be a non-regular context-free language over $\Sigma$. Let $L_a = \{\epsilon\}\cup aL \cup b\Sigma^*$ and $L_b = \{\epsilon\}\cup a\Sigma^*\cup bL $. Then both $L_a$ and $L_b$ are non-regular context-free. $L_a \cup L_b = \Sigma^*$. | |
| Jul 24, 2019 at 22:28 | vote | accept | leonard9500 | ||
| Jul 24, 2019 at 20:52 | history | edited | John L. | CC BY-SA 4.0 |
Added two exercises.
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| Jul 24, 2019 at 20:08 | history | answered | John L. | CC BY-SA 4.0 |