Computer Science Weekly Newsletter

Computer Science newsletter

Top new questions this week:

Combinatory interpretation of lambda calculus

According to Peter Selinger, The Lambda Calculus is Algebraic (PDF). Early in this article he says: The combinatory interpretation of the lambda calculus is known to be imperfect, because it …

terminology lambda-calculus combinatory-logic  
asked by Simon Shine 7 votes
answered by Roy O. 4 votes

Does #$P$-Completeness imply approximation hardness?

Let $\Pi$ be some counting problem which is known to be #$P$-Complete. Does it imply that $\Pi$ is $APX$-hard (i.e. no PTAS for the problem exists unless $P=NP$)?

complexity-theory complexity-classes approximation counting  
asked by R B 6 votes
answered by David Richerby 5 votes

Recovering a point embedding from a graph with edges weighted by point distance

Suppose I give you an undirected graph with weighted edges, and tell you that each node corresponds to a point in 3d space. Whenever there's an edge between two nodes, the weight of the edge is the …

complexity-theory graph-theory computational-geometry embedding euclidean-distance  
asked by Strilanc 6 votes
answered by D.W. 5 votes

Detecting coplanarity by given pairwise distances

Consider an undirected weighted graph $G = (V,E)$, where $V \subset \mathbb{R}^3$ so the points are 3D, and the weight of an edge equals the (Euclidean) distance between its endpoints. Note that …

algorithms computational-geometry  
asked by cagirici 5 votes
answered by Strilanc 2 votes

Difference between hypervisor and exokernel

An hypervisor (1st type) is a software that creates and run virtual machines, managing guest's operative systems's requests to the hardware. An exokernel is an operative system kernel, that let's …

terminology operating-systems kernel  
asked by Mignus 5 votes
answered by Wandering Logic 4 votes

How to think about polymorphism with subtyping

The Liskov Substitution Principle states: Invariants of the supertype must be preserved in a subtype. I'm particularly interested with the intersection of this principle and polymorphism. In …

programming-languages type-theory object-oriented  
asked by sampattuzzi 4 votes
answered by Sandeep Pareek -1 votes

Does FACTORING have optimal substructure or analog to it?

Is there any approach to FACTORING that can leverage optimal substructure allowing the problem to be decomposed into smaller subproblems? That is, perhaps being unnecessarily verbose, until an easily …

optimization dynamic-programming factoring  
asked by Cris 3 votes
answered by D.W. 2 votes

Greatest hits from previous weeks:

What is the average turnaround time?

For the following jobs: The average wait time would be using a FCFS algorithm: (6-6)+(7-2)+(11-5)+(17-5)+(14-1) -> 0+5+6+10+13 -> 34/5 = 7 (6.8) What would the average turnaround time be?

algorithms operating-systems process-scheduling scheduling  
asked by Sheldon 4 votes
answered by Gilles 5 votes

What is the difference between Multiprogramming and Multitasking

I am finding it difficult to clearly differentiate between Multiprogramming and Multitasking. My primary source has been Wikipedia, but the WP article seems to be a little at odds with some less …

terminology process-scheduling  
asked by trideceth12 6 votes
answered by vonbrand 5 votes

Can you answer these?

Incorporating newline-as-statement-terminator heuristics into context-free languages

Several block structured languages (Scala, Go, Ruby, Julia, Quorum, ...) use semicolons as statement terminators, but allow newlines instead of semicolons under certain circumstances. My question is: …

context-free programming-languages pushdown-automata  
asked by Wandering Logic 2 votes

What is a semantic cognitive map

Based on: J. P. Carvalho, "On the Semantics and the Use of Fuzzy Cognitive Maps in Social Sciences" (WCCI, 2010 -- PDF) and Richard Dagan's web page Cognitive Mapping. A cognitive map consists of …

terminology weighted-graphs  
asked by Ria George 2 votes

Palstar algorithm Dynamic Programming getting the result

I recently started to read abour dynamic programming, and I am doing an exercise on it. The problem to solve: Given a String, find the least amount of palindromes it can be split into, and print out …

algorithms optimization dynamic-programming  
asked by RunOrVeith 1 vote
Subscribe to more Stack Exchange newsletters

Unsubscribe from this newsletter or change your email preferences by visiting your subscriptions page on

Questions? Comments? Let us know on our feedback site. If you no longer want to receive mail from Stack Exchange, unsubscribe from all emails.

Stack Exchange, Inc. 110 William St, 28th Floor, NY NY 10038 <3