TY - GEN

T1 - How hard is counting triangles in the streaming model?

AU - Braverman, Vladimir

AU - Ostrovsky, Rafail

AU - Vilenchik, Dan

PY - 2013/7/23

Y1 - 2013/7/23

N2 - The problem of (approximately) counting the number of triangles in a graph is one of the basic problems in graph theory. In this paper we study the problem in the streaming model. Specifically, the amount of memory required by a randomized algorithm to solve this problem. In case the algorithm is allowed one pass over the stream, we present a best possible lower bound of Ω(m) for graphs G with m edges. If a constant number of passes is allowed, we show a lower bound of Ω(m/T), T the number of triangles. We match, in some sense, this lower bound with a 2-pass O(m/T1/3)-memory algorithm that solves the problem of distinguishing graphs with no triangles from graphs with at least T triangles. We present a new graph parameter ρ(G) - the triangle density, and conjecture that the space complexity of the triangles problem is Θ(m/ρ(G)). We match this by a second algorithm that solves the distinguishing problem using O(m/ρ(G))-memory.

AB - The problem of (approximately) counting the number of triangles in a graph is one of the basic problems in graph theory. In this paper we study the problem in the streaming model. Specifically, the amount of memory required by a randomized algorithm to solve this problem. In case the algorithm is allowed one pass over the stream, we present a best possible lower bound of Ω(m) for graphs G with m edges. If a constant number of passes is allowed, we show a lower bound of Ω(m/T), T the number of triangles. We match, in some sense, this lower bound with a 2-pass O(m/T1/3)-memory algorithm that solves the problem of distinguishing graphs with no triangles from graphs with at least T triangles. We present a new graph parameter ρ(G) - the triangle density, and conjecture that the space complexity of the triangles problem is Θ(m/ρ(G)). We match this by a second algorithm that solves the distinguishing problem using O(m/ρ(G))-memory.

UR - http://www.scopus.com/inward/record.url?scp=84880276826&partnerID=8YFLogxK

U2 - 10.1007/978-3-642-39206-1_21

DO - 10.1007/978-3-642-39206-1_21

M3 - Conference contribution

AN - SCOPUS:84880276826

SN - 9783642392054

T3 - Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

SP - 244

EP - 254

BT - Automata, Languages, and Programming - 40th International Colloquium, ICALP 2013, Proceedings

T2 - 40th International Colloquium on Automata, Languages, and Programming, ICALP 2013

Y2 - 8 July 2013 through 12 July 2013

ER -