A fast randomized LOGSPACE algorithm for graph connectivity
نویسندگان
چکیده
منابع مشابه
A Fast Randomized LOGSPACE Algorithm for Graph Connectivity
We study the relationship between undirected graph reachability and graph connec-tivity, in the context of randomized LOGSPACE algorithms. Aleluinas et al. 2] show that graph reachability (checking whether there is a path connecting vertices S and T) can be decided in logarithmic space and polynomial time, by starting a random walk at S, and checking whether T is hit within some time limit. The...
متن کاملA fast randomized algorithm for orthogonal projection
We describe an algorithm that, given any full-rank matrix A having fewer rows than columns, can rapidly compute the orthogonal projection of any vector onto the null space of A, as well as the orthogonal projection onto the row space of A, provided that both A and its adjoint A can be applied rapidly to arbitrary vectors. As an intermediate step, the algorithm solves the overdetermined linear l...
متن کاملLecture 8: Undirected Connectivity is in logspace
Clearly, any of the standard search algorithms (depth-first-search, breadth-first-search etc.) solve USTCONN in linear time. Thus, the time complexity of USTCONN is wellunderstood. What we would be interested in today’s lecture is the same complexity of USTCONN. It is to be noted that the standard search algorithms perform poorly with respect to space (this is because their implementation requi...
متن کاملFast and Simple Connectivity in Graph Timelines
In this paper we study the problem of answering connectivity queries about a graph timeline. A graph timeline is a sequence of undirected graphs G1, . . . , Gt on a common set of vertices of size n such that each graph is obtained from the previous one by an addition or a deletion of a single edge. We present data structures, which preprocess the timeline and can answer the following queries: •...
متن کاملFast Algorithm for Graph Isomorphism Testing
In this paper we present a novel approach to the graph isomorphism problem. We combine a direct approach, that tries to find a mapping between the two input graphs using backtracking, with a (possibly partial) automorphism precomputing that allows to prune the search tree. We propose an algorithm, conauto, that has a space complexity of O(n log n) bits. It runs in time O(n) with high probabilit...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Theoretical Computer Science
سال: 1996
ISSN: 0304-3975
DOI: 10.1016/s0304-3975(96)00118-1