Problem Detail: The set of all Turing machines is said to be countable. The central idea of the proof of this fact is that every Turing machine can be written as a finite string of characters. I am having trouble seeing Read More …
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Can every self-modifying algorithm be modelled by a non-selfmodifying algorithm?
Problem Detail: If we have any arbitrary computer program that can modify its instructions, is it possible to simulate that program with a program that cannot modify its instructions? Edit: I am new to stackexchange so not sure if I’m allowed Read More …
What does “context” in “context-free grammar” refer to?
Problem Detail: There are lots of definitions online about what a Context-Free Grammar is, but nothing I find is satisfying my primary trouble: What context is it free of? To investigate, I Googled “context sensitive grammar” but I still failed to Read More …
Optimal Algorithm for checking if a number is a multiple of three
Problem Detail: I’m just starting a course on Computational Number Theory and have very little Computer Science background but definitely know enough about the big-O notation. I currently have an assignment to work on: An algorithm reads in the binary digits Read More …
Shortest distance between a point in A and a point in B
Problem Detail: Given two sets $A$ and $B$ each containing $n$ disjoint points in the plane, compute the shortest distance between a point in $A$ and a point in $B$, i.e., $min space {mbox{ } text{dist}(p, q) mbox{ } | Read More …
Languages that satisfy the pumping lemma but aren’t regular?
Problem Detail: Given a regular language $L$, then it is easy to prove that there is a constant $N$ such that is $sigma in L$, with $lvert sigma rvert ge N$ there exist strings $alpha$, $beta$ and $gamma$ such that $lvert Read More …
Longest path in undirected tree
Problem Detail: Given an undirected tree (with no specific root), how to find the longest path, i.e. 2 vertices that are the farthest apart from each other? There are no lengths associated with the edges (each edge has length 1 by Read More …
How to encode date as input in neural network?
Problem Detail: I am using neural networks to predict a time series. The question I’m facing now is how do I encode date/time/serial no. of each input set as an input to the neural network? Should I use 1 of C Read More …
NP-completeness of a spanning tree problem
Problem Detail: I was reviewing some NP-complete problems on this site, and I meet one interesting problem from NP completeness proof of a spanning tree problem In this problem, I am interested in the original problem, which the leaf set is Read More …
Why is Uniform cost search called “uniform” cost search?
Problem Detail: By this possibly good attempt to explain this, the “uniformity” in the Uniform cost search is actually the uniformity of the heuristic function. Is this explanation correct ? If yes, then don’t all un-informed cost searches (like BFS, DFS, Read More …
