scholarly journals Lower bounds for external memory integer sorting via network coding

2020 ◽  
Vol 63 (10) ◽  
pp. 97-105
Author(s):  
Alireza Farhadi ◽  
Mohammad Taghi Hajiaghayi ◽  
Kasper Green Larsen ◽  
Elaine Shi
2021 ◽  
pp. STOC19-87-STOC19-111
Author(s):  
Alireza Farhadi ◽  
MohammadTaghi Hajiaghayi ◽  
Kasper Green Larsen ◽  
Elaine Shi

2009 ◽  
Vol 56 (3) ◽  
pp. 1-58 ◽  
Author(s):  
Martin Grohe ◽  
André Hernich ◽  
Nicole Schweikardt

1992 ◽  
Vol 21 (407) ◽  
Author(s):  
Lars Arge ◽  
Mikael Knudsen ◽  
Kirsten Larsen

We show a relationship between the number of comparisons and the number of I/O operations needed to solve a given problem. We work in a model, where the permitted operations are l/O-operations and comparisons of two records in internal memory. An I/O- operation swaps <em>B</em> records between external memory and the internal memory (capable of holding <em>M</em> records). An algorithm for this model is called an I/O-algorithm. The main result of this paper is the following: Given an I/O-algorithm that solves an n-record problem P_n using I/O(bar{x}) I/O's on the input bar{x}, there exists an ordinary comparison algorithm that uses no more than <em>n</em> logB + I/O(bar{x}) € T_{merge}(M-B, B) comparisons on input bar{x}. T_{merge}(n, m) denotes the number of comparisons needed to merge two sorted lists of size n and m, respectively. We use the result to show lower bounds on the number of I/O-operations needed to solve the problems of sorting, removing duplicates from a multiset and determining the mode (the most frequently occurring element in a multiset). Aggarwal and Vitter have shown that the sorting bound is tight. We show the same result for the two other problems, by providing optimal algorithms.


Author(s):  
Jasper Goseling ◽  
Ryutaroh Matsumoto ◽  
Tomohiko Uyematsu ◽  
Jos H. Weber

10.37236/679 ◽  
2011 ◽  
Vol 18 (1) ◽  
Author(s):  
Demetres Christofides ◽  
Klas Markström

Riis [Electron. J. Combin., 14(1):R44, 2007] introduced a guessing game for graphs which is equivalent to finding protocols for network coding. In this paper we prove upper and lower bounds for the winning probability of the guessing game on undirected graphs. We find optimal bounds for perfect graphs and minimally imperfect graphs, and present a conjecture relating the exact value for all graphs to the fractional chromatic number.


2007 ◽  
Vol 380 (1-2) ◽  
pp. 199-217 ◽  
Author(s):  
Martin Grohe ◽  
Christoph Koch ◽  
Nicole Schweikardt

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