Problem Detail: in order to solve a DARP problem I created a Python class, that can generate random graphs. I attribute a random number to every edge which represents the cost to travel over that edge. My current solution for connecting Read More …
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[Solved]: Non-erasing Turing machines and loss of generality
Problem Detail: A non-erasing Turing machine is one that cannot replace a symbol with a blank unless the symbol under the read head is a blank. I’m trying to understand whether there is loss of generality because of this restriction. My Read More …
[Solved]: Approximation of minimum bandwidth on binary trees
Problem Detail: Minimum bandwidth problem is to a find an ordering of graph nodes on integer line that minimizes the largest distance between any two adjacent nodes. The decision problem is NP-complete even for binary trees. Complexity Results for Bandwidth Minimization. Read More …
[Solved]: Getting started with Program Analysis
Problem Detail: I’m looking for resources on getting started with program analysis. The only book I’ve found on the topic is the Nielson & Nielson book. Other than that, it seems like there are only “compiler” books where “program analysis” would Read More …
[Solved]: Counting the nodes in a network in a distributed way
Problem Detail: There is a network with $n$ nodes. Each node can contact only the neighbouring nodes (the degree of each node is bounded, if that matters). One of the nodes, say $s$, wants to know $n$. How can it do Read More …
[Solved]: Efficient bandwidth algorithm
Problem Detail: Recently I sort of stumbled on a problem of finding an efficient topology given a weighted directed graph. Consider the following scenario: Node 1 is connected to 2,3,4 at 50 Mbps. Node 1 has 100 Mbps network card. Node Read More …
[Solved]: per-record timeline consistency vs. monotonic writes
Problem Detail: It seems to me that the per-record timeline consistency as defined by Cooper et al. in “PNUTS: Yahoo!’s Hosted Data Serving Platform” mimics the (older?) definition of monotonic writes. From the paper: per-record timeline consistency: all replicas of a Read More …
[Solved]: Overflow safe summation
Problem Detail: Suppose I am given $n$ fixed width integers (i.e. they fit in a register of width $w$), $a_1, a_2, dots a_n$ such that their sum $a_1 + a_2 + dots + a_n = S$ also fits in a register Read More …
[Solved]: When did polynomial-time algorithm become of interest?
Problem Detail: I would like to understand why and when polynomial algorithms became of interest. When did people realize the role and importance of efficient versus non-efficient algorithms? Did that happen when the concept of an algorithm was discovered, or the Read More …
[Solved]: How to read BNF syntax of C?
Problem Detail: Today I heard of BNF which is a language for languages. Also heard that it specifies the entire syntax of C in four pages. So I thought of checking it out. After reading through this page, I got a Read More …
