# Tagged Questions

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### Farewell 2014 welcome 2015 - “Math Golf”

In programming, Code Golf is a competition in which the participants are trying to implement an algorithm with code which is as short as possible. Also, Stack Exchange has a site dedicated to Code ...
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### Complement of a regular expression?

What is the regex for the complement of $r = b^*(ab + a^* + abb(b^+))^*$ ? I am thinking $(a+b)^*(abb)^+a^*$ since anything that contains $abb$ and is not followed by $b$'s would not be accepted ...
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### Finite state machine

I am doing discrete math, and we are studying Finite State Machines. But i am a little confuse on how to do this. Here is a question, Write a regular expression for the language, and define a finite ...
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### What is the difference between Algebraic Expressions and Polynomials?

Both are a combination of terms grouped together. What is the difference?
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### Blocks of Pyramid Pattern Expression [duplicate]

There is a pattern following, and trying to find the algebraic expression Each layer (from the top). Diagram. So the first layer has 1, second has 4, third has 9, and the fourth has 16. That's ...
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### Did I find the right expression for the regular language for this FSA?

I have the following FSA, and the regular language that I found for it: Is this language correct? It doesn't match the solution in the book, but my teacher says there can be multiple equally ...
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### regular language proof, a language partial to a regular one

So, I've been trying to solve a question I got and I think I'm correct but I'm not positive. Is the language {w| www belongs to L' and L' is regular} regular? I couldnt find any way to prove it isnt ...
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### $L_1 =(a^nb^n)$ and $L_2 =(a^nb^{2n})$. Is $L_1 \cup L_2$ DCFL?

I think that since $a^nb^n$ is not regular (applied pumping lemma), so is $L_2$. Therefore, $L_1 \cup L_2$ is not cfL. Is that correct?
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### Binomial theorem - number of terms in expansion

Question: Find the number of terms, after simplifying, in $$(x + y + \frac{1}{x} + \frac{1}{y})^{16}$$ I was unable to find any approach to this question. Fully expanding the expression isn't a ...
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### Expression of Equation

Find the next three terms for the pattern following : (-1276),(+425),(-142),(+47) Simple pattern here.... Only pattern I can find is that, the odd number term goes up by 1134, and the even number ...
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### Finding expression for pattern

This seems easy.... Pattern: 3, 6, 10, 15, 21.... How do I find expression for this? It looked easy, but I couldn't find it. I tried graphing it, but it turned out that it is not quadratic... ...
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### Regular expression with xor [duplicate]

Can anyone help me with this question: I know i asked a similar question not a while ago but i'm not able to understand how its possible. If anyone could give me a lot of examples instead of an ...
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### Express $y$ in terms of $x$

After solving some differential equation I arrived at $$2ln(y-1) +(y-1)=(x-3)+3 ln(x-3)+c$$ but I can't write $y$ in terms of $x$ to find explicit solution.
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### Are regular expressions in mathematics related to PCRE or POSIX regexps?

I've recently come across a number of questions tagged with (regular-expressions), and talking about some type of regular expressions, here's an example of such ...
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### Regular expression 00 or 11 not both

Can anyone help me with this question: I know it before, but I have tried to solve it myself and didnt succeed. what is the regular expression for this language: L=all words that have 00 or 11 but not ...
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### Regular expression problem

I have this question and no clue how to solve. Thanks for your help I need to build the regular expression matching this language $$L=\{ 0^m~1^n | (m+n) \pmod 3 = 1 \}$$