The tag has no wiki summary.

learn more… | top users | synonyms

0
votes
0answers
26 views

Clarification needed on a proposed algorithm in a published paper called PAU-DL

There is an algorithm called Parallel Atom-Updating Dictionary Learning (PAU-DL) in the context of image and video processing, dictionary learning. I read about it in this published paper: ...
1
vote
0answers
62 views

Minimum size counter-example in a 2-machine scheduling problem proof

I'm confused about something in the main proof in this paper (sorry that it's behind a paywall, but I assume many people on here have access to such things through their university and my posting the ...
1
vote
0answers
65 views

Follow the Perturbed Leader for nonlinear cost functions

The famous FTPL algorithm [1] is analyzing linear cost function. Is there any generalized proof for nonlinear functions known? Note that in the last paragraph of [1] it says "It would be great to ...
1
vote
2answers
101 views

Sketches, using ideal hash functions

I've been reading about sketches for processing streaming data (the CountMin sketch, the Count sketch, the tug-of-war sketch, FM sketches, etc.). They use hash functions that are required to be ...
6
votes
2answers
280 views

Streaming algorithms suitable for undergrad course

I am looking for interesting streaming algorithms that would be suitable for presentation in an undergraduate algorithms course. Good choices should probably satisfy the following requirements: ...
1
vote
0answers
112 views

Automatically Adapting Forgetting Factor for Online EM

I've been reading some interesting papers recently on methods for automatically and adaptively setting the learning rate in stochastic gradient descent (SGD). In particular, "No more pesky learning ...
1
vote
1answer
69 views

Are there published algorithms for on-line creation of AVL trees from ordered streams?

Given an ordered stream of n items (n unknown in advance), it is well-known how to construct a red-black tree from them in O(n)-time. More specifically this is possible using only O(log n) additional ...
20
votes
1answer
297 views

Languages recognized by polynomial-size DFAs

For a fixed finite alphabet $\Sigma$, a formal language $L$ over $\Sigma$ is regular if there exists a deterministic finite automaton (DFA) over $\Sigma$ which accepts exactly $L$. I am interested in ...
3
votes
1answer
227 views

Definition of fractional in theoretical CS

What is the definition of the word "fractional" in algorithms? I have encountered the word in phrases like "fractional algorithm", "fractional node routing problem". Note: English is not my native ...
2
votes
2answers
65 views

Fast algorithm for linear context finding

I am trying to figure out a quick algorithm which solves the following problem. For the rest of this question, assume $0\in\mathbb{N}$. Denote by $\mathbb{R}^\mathbb{N}$ the set of all real ...
3
votes
0answers
183 views

Is there an online algorithm for solving any P-complete problem?

We can think of the class $NC$ as the class of problems that can be solved in parallel, whereas a $P$-complete problem probably has no parallel solution. My question is: where do online algorithms ...
6
votes
2answers
215 views

Maintaining the product of a queue of semigroup elements

I have a queue $Q$ where elements can be popped from the left and added to the right in $O(1)$ time. The elements are members of a fixed semigroup $S$ with $O(1)$ time multiplication. Let the ...
0
votes
1answer
126 views

Capacity planning algorithm resources

Let's say I have a machine with many boxes of different sizes. I want to put packages inside those boxes. Packages arrive at different time and then stay in the box for specific period of time. I need ...
2
votes
0answers
55 views

Scheduling with RSVP deadline and possible cancellations

There is a sequence of events $e_1,\ldots,e_n$. $s(e_i), t(e_i)$ and $w(e_i)$ is the starting, terminating time and the weight of $e_i$, respectively. $p(e_i)$ is the probability of the event getting ...
14
votes
1answer
333 views

Is it enough for linear program constraints to be satisfied in expectation?

In the paper Randomized Primal-Dual analysis of RANKING for Online Bipartite Matching, while proving that the RANKING algorithm is $\left(1 - \frac{1}{e}\right)$-competitive, the authors show that the ...
11
votes
1answer
470 views

Online Algorithms books

Are there any recent books on Online Algorithms? I know of only two books on the subject. Online Computation and Competitive Analysis by Allan Borodin and Ran El-Yaniv: This is a classic but old ...
6
votes
1answer
177 views

What are good set size estimation algorithms for small sets (around 10-50 elements)?

I'm trying to implement an online distinct counting algorithm, and I have thousands of small sets of 32 bit IP addresses whose sizes I want to estimate with high accuracy (1-5%). I came across quite ...
8
votes
2answers
248 views

Cheap online selection with weighted comparisons

Suppose we want to find the smallest element of a set $S$, whose elements are indexed from $1$ to $n$. We do not have access to the values of these elements, but we can compare any two elements of ...
4
votes
0answers
122 views

Online Interval Coloring Problem

We are given a path $P = (V,E)$ on $n$ nodes, where each edge $e \in E$ has a capacity $c_e$. There are a set of $k$ requests $R_1,\ldots,R_k$. Request $R_i$ has a demand $d_i$, and has an interval ...
1
vote
0answers
101 views

Competitive ratio of Move To Front in alternate access - List Update Problem

I need to prove that the modification of MTF, Move to front on every even request of an element, list update problem has a competitive ratio of 2. How does one go about proving such results? (I'm ...
6
votes
2answers
152 views

Can a non-competitive deterministic algorithm be k-competitive if randomized?

Let's say there is a problem in which all possible deterministic online algorithms tha solve this problem are not-competitive. Does this mean that a randomized online algorithm for the same problem ...
6
votes
0answers
272 views

View of Multiplicative Weights in contexts of combinatorial optimization, low-regret/online optimization, and entropy-regularized gradient descent?

Also called exponentiated gradient. I understand these are three places where multiplicative weights shows up (i.e. $w_{t+1} = w_{t}e^{- \text{loss}(w_{t})}$ or variations. And I understand a bit ...
5
votes
2answers
948 views

Brackets expression incremental parsing algorithm

I am looking for efficient and easy in implementation algorithm for incremental parsing of expressions with brackets. Consider the example with expression like "((1)())(2)". Parse tree for that ...
17
votes
2answers
373 views

Does an algorithm exist to efficiently maintain connectedness information for a DAG in presence of inserts/deletes?

Given a directed acyclic graph, $G(V,E)$, is it possible to efficiently support the following operations? $isConnected(G,a,b)$: Determines if there is a path in $G$ from node $a$ to node $b$ ...
1
vote
1answer
173 views

Has this online problem been studied before ?

Consider the following online problem: For $\sigma$ and $k$ fixed, given a string of symbols from alphabet $[1..\sigma]$, given one by one, guess a set $S$ of $k$ symbols such that the next ...
19
votes
2answers
585 views

maintaining a balanced spanning tree of a growing undirected graph

I am looking for ways to maintain a relatively balanced spanning tree of a graph, as I add new nodes/edges to the graph. I have an undirected graph that starts as a single node, the "root". At each ...
7
votes
1answer
1k views

What's the difference between online and incremental optimization?

Recently I've read some stuff about incremental optimization problems, but I can't see what's the difference between those and online optimization problems. My impression is that I can define every ...
17
votes
3answers
308 views

Is there a constant factor approximation algorithm for 2D rectangle coloring problem?

The problem we consider here is the extension of the well-known interval coloring problem. Instead of intervals we consider rectangles having sides parallel to axes. The objective is to color the ...
11
votes
3answers
1k views

Is there an online-algorithm to keep track of components in a changing undirected graph?

Problem I have an undirected graph (with multi-edges), which will change over time, nodes and edges may be inserted and deleted. On each modification of the graph, I have to update the connected ...
18
votes
2answers
4k views

Algorithm for 'k'' most frequently occurring numbers

I have been searching for the most efficient (streaming??) algorithm that tells me the 'k' most frequently occurring elements in a data stream at any point in time. This post: ...
8
votes
4answers
320 views

Continuous Clustering

So I have an issue I'm facing in regards to clustering with live, continuously streaming data. Since I have an ever-growing data set I'm not sure what is the best way to run efficient and effective ...