Problem Detail: In other words, is there a relationship between the step size and the actual running time? Suppose that the algorithm is run on identical machine. Asked By : Beached Whale Answered By : David Richerby There’s no clear relationship, except that Read More …
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[Solved]: Measuring the difficulty of SAT instances
Problem Detail: Given an instance of SAT, I would like to be able to estimate how difficult it will be to solve the instance. One way is to run existing solvers, but that kind of defeats the purpose of estimating difficulty. Read More …
[Solved]: Studying Programming Language Theory
Problem Detail: I have recently become extremely interested in understanding and proving aspects of (functional) programming languages. However as I dive deeper in, things like $lambda$ calculus, category theory, and denotational semantics are a little difficult to grok without proper explanation. Read More …
[Solved]: Turing Machine for strings without bbb
Problem Detail: I am trying to generate a transition graph for a turing machine that accepts the languages of all strings that do not contain the substring $bbb$ with the input alphabet $Sigma = {a, b}$. When I implement this graph Read More …
[Solved]: What exactly is a hash function?
Problem Detail: I have no idea how I managed to get this far in life without ever really grasping this but as it happens I’m still very confused on the concept of a hash function. I did some googling/wikipedia-ing, and here’s Read More …
[Solved]: Reducing a problem to Halt
Problem Detail: I’m reviewing for a computability test, and my professor has not provided solutions to his practice questions. I came up with a “solution” to this problem, but it really seems like my answer is wrong (since I call upon Read More …
[Solved]: How is a witness found in a proof of $mathsf{NP} subseteq mathsf{P}/log implies mathsf{P} = mathsf{NP}$?
Problem Detail: I’m having a hard time understanding the actual proof of this proposition: $qquad mathsf{NP} subseteq mathsf{P}/log implies mathsf{P} = mathsf{NP}$ The sketch of the proof is on slides 6-8 of this PDF. So I let $L in mathsf{NP}$. That Read More …
[Solved]: How can GIF compression be lossless if the maximum # of colors is 256?
Problem Detail: I’m reading “Computer Science Made Simple” by V. Anton Spraul, and in the chapter about Graphics, he describes GIF files as follows: A GIF file uses lossless compression to store an image with a maximum of 256 different colors. Read More …
[Solved]: Why don’t modern SAT solvers use the notion of a “watched clause”, in the same way they use the notion of a “watched literal”?
Problem Detail: Modern SAT solvers use the notion of “watched literals”: when a value is chosen for a literal $l$, the solver only checks whether that falsifies clauses with $l$ in them if $l$ is one of the watched literals in Read More …
[Solved]: Will floating point code return the same arithmetical results on two different computers?
Problem Detail: Say I am using boost or the built-in float or double mathematical libraries of my C++ compiler. I distribute the program. Will the execution of my C++ program on different machines given different floating point results given that the Read More …
