Questions tagged [dc.distributed-comp]

Theoretical questions in Distributed Computing

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Application LCL definition to vertex coloration

I'm reading the article "What can be computed locally?" by Naor & Stockmeyer and I struggle to understand the definition of an LCL they gave. Here is an extract: (page 2) An Locally ...
0 votes
0 answers
20 views

The minimal number of messages required to solve the mutual exclusion problem in a symmetric distributed system

In the seminal paper introducing their namesake algorithm for solving the mutual exclusion problem in a distributed system, Ricart and Agrawala assert (in the first paragraph of section 4 Message ...
1 vote
1 answer
43 views

Sequential idempotence

I want to coalesce multiple operations in a system into one and am currently studying under what conditions it is admissible. The conditions that are needed are stronger than idempotence and I'm ...
0 votes
1 answer
54 views

Selecting unique records from a large dataframe with many duplicate records

Suppose we have a dataframe with ~10M rows with ~9M duplicate records. What is the most time efficient way of selecting the unique records from this dataframe? Some sort of sampling algorithm?
44 votes
4 answers
2k views

Why have we not been able to develop a unified complexity theory of distributed computing?

The field of distributed computing has fallen woefully short in developing a single mathematical theory to describe distributed algorithms. There are several 'models' and frameworks of distributed ...
3 votes
2 answers
650 views

What is "distributed computing" as a field of computer science?

I think it's field that studies distributed systems as described at http://en.wikipedia.org/wiki/Distributed_computing. There are distributed systems such as clusters and grids on top of this field. ...
3 votes
1 answer
98 views

Lipschitz composable compressor

Def. We call $C: \mathbb R^d \to \mathbb R^d$ a $\delta$-compressor (or contractor) if for all $x$ $$\|C(x) - x\|^2 \le (1 - \delta) \|x\|^2$$ Intuitively, $C(x)$ is not too far from $x$. Note that $\...
1 vote
2 answers
205 views

Can concurrency models be compared in terms of some metrics?

In Seven Concurrency Models in Seven Weeks by Butcher, it compares Actor Model and Communicating Sequential Processes (CSP): CSP is more flexible than actor model: In actor model, the medium of ...
-2 votes
1 answer
1k views

Sequential vs Distributed algo question

If a certain graph problem in the $\textbf{sequential}$ setting is proven to have "no" better constant-factor approximation algorithm than say a 2-approx. algorithm in polynomial time, then does this ...
2 votes
1 answer
431 views

The proof of P2b in Paxos made simple

I am reading Paxos Made Simple. I am quite confused about the proof of P2b. It said We would make the proof easier by using induction on n, so we can prove that proposal number n has value v under ...
1 vote
0 answers
54 views

How to justify this causally consistent execution in the $(vis, ar)$ framework for distributed consistency models?

In Figure 5.1 of the book "Principles of Eventual Consistency" by Sebastin Burckhardt, 2014, Causal Consistency (CC); wiki is (mainly) defined as the conjunction of $hb \subseteq vis$ and $hb \...
1 vote
0 answers
110 views

Confusion about the visibility and arbitration relations in a formal framework for distributed consistency models

In the POPL'14 paper "Replicated Data Types: Specification, Verification, Optimality" and the book "Principles of Eventual Consistency", the authors propose a formal framework for ...
5 votes
1 answer
713 views

Modern distributed computing book

Lynch's Distributed Algorithms book is a classic but it is from 1996 and rather out of date. Are there any recent distributed computing books that can be used as textbooks for a graduate distributed ...
-1 votes
1 answer
80 views

How to know if a problem is distributable?

I am new to the world of Parallel computing and that is why don't know exactly where I should look at or search to get the answer. Is there any theorem or just general theory determining which code ...
5 votes
1 answer
235 views

Confusion about a formal definition of PRAM consistency

I am reading the paper "Consistency in Non-Transactional Distributed Storage Systems" by Paolo Viotti and Marko Vukolić. The authors provide a comprehensive survey of various consistency semantics ...
4 votes
3 answers
546 views

What does it mean for CvRDT replicas to transmit their state "infinitely often"?

In Shapiro et al.'s SSS '11 paper on Conflict-Free Replicated Data Types for eventual consistency of distributed replicated objects, they describe a system model in which replicas transmit their state ...
4 votes
1 answer
123 views

"Learning" when test and train distributions don't match

We know that the theory of PAC-learning is distribution-free, i.e. assuming that the test and train distributions are the same, we have guarantees on learning the hypothesis. Question: what if the ...
3 votes
1 answer
58 views

Complexity of distributively verifying that the diameter is small

Consider a graph $G=(V,E)$ and an integer parameter $k$. I'm interested in the round complexity, in the CONGEST model, of checking if the diameter of the graph is "much larger" or "much smaller" than ...
4 votes
0 answers
145 views

2-hop distributed coloring in the CONGEST model

Consider a graph $G=(V,E)$ and let $d(u,v)$ denote the distance between $u$ and $v$ in $G$. A 2-hop coloring is a mapping $c:V\to{1,\ldots, C}$ ($C$ is the number of colors) such that $d(u,v)\le 2 \...
1 vote
1 answer
80 views

Does the following 2-rounds distributed algorithm approximates a maximal matching well?

Let $G$ be an undirected graph. I'm looking for a two-rounds distributed algorithm that matches as many vertex pairs as possible. Consider the following protocol for vertex $v$. Use a fair coin to ...
-3 votes
1 answer
159 views

Continous work distribution algorithm with failover

Imagine there's a system where there's N workers and M units of work, for example, N ≤ 64, M = 256. Is there an algorithm that ...
3 votes
0 answers
142 views

How does communication complexity relate to time complexity in distributed algorithms?

Some distributed algorithms (e.g. Bracha broadcast) runs in a constant number of rounds. I'm interested on how you'd analyse the time complexity of such algorithm, especially when the message size ...
2 votes
1 answer
468 views

Paxos made simple, invariant P2c

I am reading Leslie Lamport's Paxos Made Simple paper. Can someone explain why $P2^c$ implies $P2^b$? $P2^b$ If a proposal with value $v$ is chosen, then every higher-numbered proposal issued ...
1 vote
0 answers
103 views

How to design a scalable distributed consensus protocol that isn't vulnerable to long range attack

Research on distributed consensus has surged with the invention of Bitcoin and Blockchain. In these special cases we are looking for a distributed consensus algorithm that can scale to a number of ...
2 votes
1 answer
102 views

Why do timeouts require synchronized clocks?

In Impossibility of distributed consensus with one faulty process @1985 by Fischer at al., the authors state (p375) We also assume that processes do not have access to synchronized clocks, so ...
7 votes
1 answer
145 views

Confusions about the technique for verifying implementations of linearizable objects in [Herlihy and Wing, 1990]

In Section 4.3.2 entitled "Proof Method" of Herlihy and Wing, "Linearizability: A Correctness Condition for Concurrent Objects", 1990 the authors describe the technique for verifying ...
14 votes
4 answers
635 views

Infinitely large but locally finite computation problems

This question is inspired by a comment Jukka Suomela made on another question. What are examples of infinitely large but locally finite computation problems (and algorithms)? In other words, what ...
1 vote
2 answers
272 views

Distributed Consistency using Quorum approach

I'm stuck at distributed consistency when using a quorum. In this case we use N servers - 2/3N+1 for the read quorum (Nr), and <...
16 votes
0 answers
168 views

Is it possible to boost the error probability of a Consensus protocol over dynamic network?

Consider the binary consensus problem in a synchronous setting over dynamic network (thus, there are $n$ nodes, and some of them are connected by edges that may change round to round). Given a ...
19 votes
4 answers
11k views

Why is the consensus problem so important in distributed computing?

In distributed computing, the consensus problem seems to be one of the central topics which has attracted intensive research. In particular, the paper "Impossibility of Distributed Consensus with One ...
-3 votes
1 answer
71 views

Is it correct to call systems with agents without BDI multi-agent systems? [closed]

The question concerns two fields - multiagent systems in AI and in software engineering. As the source of the term comes from the AI field, I ask the question here. Traditionally multiagent system (...
3 votes
1 answer
166 views

Does such model exists?

I have a problem on distributed graph, with the following model: 1. There is a Global Graph $G=(V,E)$ 2. There are $k$ computers. 3. Each computer $1 \leq i \leq k$ knows ALL the nodes of the graph,...
0 votes
1 answer
77 views

Number of rounds of iterative one-round distributed color reduction

We are talking about one-round coloring algorithms for distributed graphs. In "On the complexity of distributed graph coloring" (theorem 5.1) Kuhn and Wattenhoffer presented a one-round algorithm to ...
0 votes
1 answer
165 views

What do these lower bounds really mean?

I was reading an abstract for a paper that gives a minimum number M of good agents that guarantees f-Byzantine gathering, if there are f Byzantine agents. It gives a lower bound of f+1 for strongly ...
1 vote
1 answer
82 views

What does the contention-free communication assumption really mean in the context of DAG scheduling?

In many papers about DAG (directed-acyclic graph) scheduling in distributed systems, the authors make the assumption that the communication between the processors of the system where the DAG is ...
2 votes
0 answers
45 views

centralized deterministic Spanner construction with low degree and low stretch

Does there exist a centralized deterministic spanner construction with low degree and low stretch both independent of the graph diameter (no log D factor), but can be dependent on the number of nodes. ...
2 votes
1 answer
82 views

How to simulate sequential registers from causal ones?

Background: In distributed shared memory (DSM) model, the problem of register simulations/constructions is to simulate registers with certain characteristic out of registers with weaker features. For ...
27 votes
4 answers
10k views

Major unsolved problems in distributed systems?

Inspired by this question, what are the major problems and existing solutions which needs improvement in (theoretical) distributed systems domain. Something like membership protocols, data ...
3 votes
0 answers
267 views

Atomic snapshot algorithms on tree-structured shared registers

Background: Atomic snapshot memory is a shared memory partitioned into words written (updated) by individual processes, or instantaneously read (scanned) in its entirety. The Gang of Six algorithm ...
3 votes
1 answer
103 views

Results about computability power or limitations of shared read/write registers

I want to know more results about the computability power or limitations of shared $\texttt{read/write}$ registers/objects in distributed/concurrent computing theory. Two typical examples are: [1]. ...
0 votes
1 answer
57 views

Proof of causal multicast algorithm?

I'm reading Causal Memory: Denitions, Implementation and Programming and trying to get through the proof of liveliness of the algorithm around the middle of page 9, and I'm not really following it. ...
3 votes
1 answer
114 views

Lower bounds and impossibility results for distributed transactions

I am studying on distributed transactions, mainly on the correctness criteria (e.g., serializability (SR) and snapshot isolation (SI) in replicated settings) and their implementations. To avoid ...
3 votes
0 answers
227 views

In what sense, does a safe register exist?

In the paper "On Interprocess Communication", the author Leslie Lamport have developed a formalism for interprocess communication via shared registers based on lower-level, non-atomic operations and ...
10 votes
1 answer
640 views

What are the major research issues in distributed transactions?

Background: Transaction processing has been a traditional research topic in database theory. Nowadays distributed transactions are popularized by the large-scale distributed storage systems which ...
2 votes
1 answer
290 views

State of the art algorithms for community detection in graphs

Is anyone aware of the must read papers to get knowledge of the most recent algorithms and method for community detection in graphs, especially those that represent social networks?
-2 votes
1 answer
204 views

What are some natural problems that we can quickly find a solution to using massive parallelism but not a canonical solution?

For many problems, more than one output is acceptable. For instance, the problem of finding an assignment that satisfies a boolean formula. If randomness buys us something then it could be that it ...
13 votes
1 answer
1k views

Correctness proofs of classic Paxos and Fast Paxos

I am reading the "Fast Paxos" paper by Leslie Lamport and get stuck with the correctness proofs of both classic Paxos and Fast Paxos. For consistency, the value $v$ picked by the coordinator in phase ...
5 votes
0 answers
140 views

What is the significance of regarding the mutual exclusion problem as a problem of physics?

In the description of his own paper "On Interprocess Communication" [Distributed Computing 1, 2 (1986), 77-101], Leslie Lamport wrote Most computer scientists regard synchronization problems, such ...
9 votes
1 answer
783 views

Is linearizability equivalent to consensus problem?

In the introduction of this paper Eventually Linearizable Shared Objects (PODC'10), the authors have presented the following statement without references: Linearizability, however, can be achieved ...
3 votes
1 answer
294 views

Concurrent data structures vs. Distributed data structures

In the context of multi-processor/multi-threaded systems, there are plenty of well-studied concurrent data structures, including stacks, queues, linked lists, etc. Here is an excellent survey on ...