A Logspace Algorithm for Partial 2-Tree Canonization

نویسندگان

  • Vikraman Arvind
  • Bireswar Das
  • Johannes Köbler
چکیده

We show that partial 2-tree canonization, and hence isomorphism testing for partial 2-trees, is in deterministic logspace. Our algorithm involves two steps: (a) We exploit the “tree of cycles” property of biconnected partial 2-trees to canonize them in logspace. (b) We analyze Lindell’s tree canonization algorithm and show that canonizing general partial 2-trees is also in logspace, using the algorithm to canonize biconnected partial 2-trees.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

The Isomorphism Problem for k-Trees Is Complete for Logspace

We show that, for k constant, k-tree isomorphism can be decided in logarithmic space by giving a logspace canonical labeling algorithm. The algorithm computes a unique tree decomposition, uses colors to fully encode the structure of the original graph in the decomposition tree and invokes Lindell’s tree canonization algorithm. As a consequence, the isomorphism, the automorphism, as well as the ...

متن کامل

The Space Complexity of k -Tree Isomorphism

We show that isomorphism testing of k-trees is in the class StUSPACE(log n) (strongly unambiguous logspace). This bound follows from a deterministic logspace algorithm that accesses a strongly unambiguous logspace oracle for canonizing k-trees. Further we give a logspace canonization algorithm for k-paths.

متن کامل

Helly Circular-Arc Graph Isomorphism Is in Logspace

We present logspace algorithms for the canonical labeling problem and the representation problem of Helly circular-arc (HCA) graphs. The first step is a reduction to canonical labeling and representation of interval intersection matrices. In a second step, the Δ trees employed in McConnell’s linear time representation algorithm for interval matrices are adapted to the logspace setting and endow...

متن کامل

Interval Graphs: Canonical Representations in Logspace

We present a logspace algorithm for computing a canonical labeling, in fact a canonical interval representation, for interval graphs. To achieve this, we compute canonical interval representations of interval hypergraphs. This approach also yields a canonical labeling of convex graphs. As a consequence, the isomorphism and automorphism problems for these graph classes are solvable in logspace. ...

متن کامل

Graphs of Bounded Treewidth can be Canonized in AC

In recent results the complexity of isomorphism testing on graphs of bounded treewidth is improved to TC [GV06] and further to LogCFL [DTW10]. The computation of canonical forms or a canonical labeling provides more information than isomorphism testing. Whether canonization is in NC or even TC was stated as an open question in [Köb06]. Köbler and Verbitsky [KV08] give a TC canonical labeling al...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2008