Questions tagged [fine-grained-analysis]

Analyzing the asymptotic complexity of problems already known to be polynomial time solvable. Often, conditional lower bounds are used to show that a specific algorithm is asymptotically optimal.

Fine-Grained Analysis

This term have been used frequently in recent papers, to indicate to analyses of algorithms/reduction with high attention to details of the given method. In contrast to coarse-grained analysis, fine-grained analysis contains deeper inspecting of single steps. It sets finer bounds on the running times and the constructed structures to achieve finer total running time. It is used mostly in conditional lower-bound, string matching algorithms and distributed models of computing.

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An example where the algorithm of Hopcroft and Karp performs poorly?

I have been trying to construct an example, where Hopcroft and Karp's algorithm for the maximum matching problem performs poorly (say at least $\Omega(\log n)$ rounds). However, all the examples I came up with where solved on paper in almost…
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Conditional lower bounds on the running time of the single source shortest path problem

Just out of curiosity, I was wondering whether there is a conditional lower-bound on the running time of an algorithm for the Single Source Shortest Path Problem (on directed or undirected graphs). I found papers with lower-bounds on some special…
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Usage of matrix multiplication for distance products

This is more of a validation question, for the current best known results. On one hand, we have classical matrix multiplication. Its running time is denoted as $n^\omega$. On the other, we have distance products, where an operation similar to matrix…
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Can fine-grained hardness be proved directly from classical hardness (e.g., $\sf P \neq NP$) in some way?

I have just learnt about some typical result of fine-grained hardness in 15-455 by Prof Ryan: CNF-SETH implies ${\sf DIAMETER} \notin {\sf TIME}(mn^{1-\epsilon})$. (Here DIAMETER stands for the graph diameter problem). To prove fine-grained…
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Classical matrix multiplication via Min-Plus matrix multiplication

Just a thought I had in mind. I can use classical matrix multiplication to compute min-plus matrix multiplication. Generally speaking, considering $(n+1)^{a_{i,j}}$ for each entry and then taking the smallest value. But what about the other way…
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3SUM Reduction to Distinct Pairwise Sum

The 3SUM problem is defined as follows: Given three sets of integers $A,B,C \subseteq \{-W,\ldots,W\}$ for $W = n^3$, each containing $n$ integers, determine whether there exsists some $a \in A, b \in B, c \in C$ such that $a+b+c=0$. The X+Y problem…
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Approximating shortest paths on weighted directed graphs

I have recently come across the paper Fast 2-Approximate All-Pairs Shortest Paths. The authors state, in pg.1 of the introduction, that, given a directed, weighted graph, approximating the distances between any two vertices (that is, approximating…
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