# Is this language equivalent to this grammar?

The book that I'm reading says it is equivalent

But what about the aa string ? i produce it this way :

$$S\Rightarrow S_1B\Rightarrow aS_1bB\Rightarrow aaB\Rightarrow aa$$ But that language doesn't have aa in it, what am i doing wrong here?

• Could you please replace the image with text? – fade2black Sep 27 '17 at 16:52
• Is it common to typeset one and zero like that? – Tomoki Sep 27 '17 at 16:54
• Your derivation is correct. If you quoted correctly, the book is wrong. – Rick Decker Sep 27 '17 at 16:55
• Welcome to Computer Science! Note that you can use LaTeX here to typeset mathematics in a more readable way. See here for a short introduction. – Raphael Sep 27 '17 at 17:07
• You can try proving the claim and see how it goes. – Raphael Sep 27 '17 at 17:07