Problem Detail: Many sites give the Sobel operators as the convolution mask for smoothing an image. However, I haven’t found a single site that describes how you can derive the operators from partial first derivatives. If anyone can explain the derivation, Read More …
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Convex polygon formulation
Problem Detail: We have a sorted list of side lengths that can be used to form a polygon. There are $n$ such values ($n le 1000$). Now we need to find if we can use any 10 of these values to Read More …
How are all NP Complete problems similar?
Problem Detail: I’m reading few proofs which prove a given problem is NP complete. The proof technique has following steps. Prove that current problem is NP, i.e., given a certificate, prove that it can be verified in polynomial time. Take any Read More …
Is this grammar LR(1)
Problem Detail: I am reading parser chapter from dragon book and I found a grammar over there – $ S rightarrow L=R $ $ S rightarrow R $ $L rightarrow *R $ $L rightarrow id $ $R rightarrow L $ Now Read More …
Algorithm to determine whether two regexes are equivalent
Problem Detail: Given two arbitrary regular expressions, is there an “efficient” algorithm to determine whether they match the same set of strings? More generally, can we compute the size of the intersection of the two match sets? What algorithms are there Read More …
An oracle to separate NP from coNP
Problem Detail: How to prove that $mathsf{NP}^A neq mathsf{coNP}^A$ ? I am just looking for a such oracle TM $M$ and a recursive language $L(M) = L$ for which this holds. I know the proof where you show that there is Read More …
Do not understand why log n = O(n^c) (for any c>0)
Problem Detail: Can anyone help me understand this equation? $log (n) = O(n^c)$ (for any $c>0$) Does it mean that $O(log (n)) < O(n^c)$ (for any $c>0$)? Added: Please also prove that $log (n) = O(n^c)$ is true. Asked By : Xin Read More …
Books to prepare before reading Knuth’s The Art Of Computer Programming (TAOCP)
Problem Detail: Many people say that TAOCP is not supposed to be read as a book (actually a volume of books), but if I decide to go that way, which math/computer science books/topics do I need to study to help me Read More …
How does binary addition work?
Problem Detail: I find binary confusing. I have watched minecraft redstone videos on binary adders, real binary adders, diagrams, etc and yet I have not learned much at all. How does electrons flowing through wires made of gold “add/subtract” to make Read More …
What is the purpose of Mark field in Fibonacci Heaps?
Problem Detail: In Fibonacci heaps, we keep a mark field for every node in the heap. Initially all the nodes are unmarked. Once a node is deleted, its parent is marked. If a node is deleted and its parent is already Read More …
