## #math - Tue 24 Apr 2007 between 06:33 and 06:39

### NY Lost Funds

 Cale f(x+dx)?are you working with infinitesimals? kmh Manyfold : you mean the derivative ? FatalErrorX Manyfold: join the club Manyfold which club Cale Nothing in the preconditions Guest57536 gave indicate that f is differentiable. kmh Manyfold : of unanswered questions ?:) FatalErrorX the not getting questions answered club Manyfold f(x+dx) means that it is infinitesimal greate than f(x) |Steve| FreeNode is great for category and algebra questions. Cale FatalErrorX: do you know how to write matched brackets as a CFG? Manyfold i mean the argument FatalErrorX i guess not so good for computational theory questions |Steve| Actually, that's my area, I just wasn't paying attention. =) FatalErrorX lol kmh FatalErrorX . depends who's around FatalErrorX can anyone help me write [{a,b}* | at least as many a's as b's] as a CFG Manyfold CFG? |Steve| That's easy. FatalErrorX Context free grammer:) kmh FatalErrorX : there is no your-question-has-to-be-answered-policy here |Steve| S -> aSb | A; A -> aA | \varepsilon. Cale FatalErrorX: do you know how to write matched brackets as a CFG? |Steve| Bam! FatalErrorX Cale: ? Cale only |Steve|'s interpretation puts all the a's first, and all the b's after. FatalErrorX |Steve|: thankyou Cale So it's not quite right. |Steve| Oh, that's what I thought you want, silly me.I did a^nb^m n >= m. FatalErrorX lol |Steve| So this is also easy, every time you put in a b, you have to add an a. Cale How about S = aSb | bSa | aS | Sa | epsilon |Steve| And that's it.Although it should really be an arrow ->. FatalErrorX ya Cale So, prove that every string of the language is generated by that grammar. FatalErrorX thankyou both Cale The other direction is easy.