Problem Detail: We learned about the concept of enumerations of functions. In practice, they correspond to programming languages. In a passing remark, the professor mentioned that the class of all total functions (i.e. the functions that always terminate for every input) Read More …
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Shortest path in weighted(positive or negative) undirected graph
Problem Detail: I have to find an algorithm that finds the SSSP (single-source shortest path – shortest paths from one source vertex to all other vertices) on a weighted undirected graph. If there are 2 different shortest paths, the algorithm should Read More …
Why is the name half-adder used to represent the half-adder?
Problem Detail: I have recently came across half-adders and full adders in my Logic Network lectures. I have somewhat understood the theory, but I am still unable to understand the reason why they called them in that name? I mean, is Read More …
Differences between SISD, SIMD and MIMD architecture (Flynn classification)
Problem Detail: I have a problem with classifying certain CPUs to the proper classes of Flynn’s Taxonomy. 1. Zilog Z80 According to this article on Sega Retro, Z80 has limited abilities to be classified as SIMD: a limited ability for SIMD Read More …
NP-Hard problems that are not in NP but decidable
Problem Detail: I’m wondering if there is a good example for an easy to understand NP-Hard problem that is not NP-Complete and not undecidable? For example, the halting problem is NP-Hard, not NP-Complete, but is undecidable. I believe that this means Read More …
A Question relating to a Turing Machine with a useless state
Problem Detail: OK, so here is a question from a past test in my Theory of Computation class: A useless state in a TM is one that is never entered on any input string. Let $$mathrm{USELESS}_{mathrm{TM}} = {langle M, q rangle Read More …
DFA to regular expression conversion
Problem Detail: I was looking at the question How to convert finite automata to regular expressions? to convert DFA to regex. The question, I was trying to solve is: I have got the following equations: $Q_0=aQ_0 cup bQ_1 cup epsilon$ $Q_1=aQ_1 Read More …
Can random suitless $52$ playing card data be compressed to approach, match, or even beat entropy encoding storage? If so, how?
Problem Detail: I have real data I am using for a simulated card game. I am only interested in the ranks of the cards, not the suits. However it is a standard $52$ card deck so there are only $4$ of Read More …
Universality of the Toffoli gate
Problem Detail: Regarding the quantum Toffoli gate: is it classicaly universal, and if so, why? is it quantumly universal, and why? Asked By : Ran G. Answered By : Artem Kaznatcheev Toffoli is universal for classical computation (as shown by @Victor). However, Toffoli Read More …
Can a Turing Machine (TM) decide whether the halting problem applies to all TMs?
Problem Detail: On this site there are many variants on the question whether TMs can decide the halting problem, whether for all other TMs or certain subsets. This question is somewhat different. It asks whether the fact the halting problem applies Read More …
