Search Results for "backtracking"

RE2/J is a high-performance regular expression engine implemented in pure Java as a port of Google’s C++ RE2 library. Unlike traditional regex engines such as Java’s java.util.regex, PCRE, or Perl’s implementation—which rely on backtracking and can suffer from catastrophic exponential runtimes—RE2/J guarantees linear-time matching relative to input size. It achieves this efficiency by simulating all possible matches in a single pass using a nondeterministic finite automaton (NFA), ensuring predictable and safe performance even with complex patterns. This makes RE2/J ideal for applications that must handle user-supplied regular expressions securely without the risk of denial-of-service through regex backtracking. ...

Tool to transcribe Parsing Expression Grammar into a parser written in Java. Parsing Expression Grammar (PEG) is a way to specify recursive-descent parsers with limited backtracking. The use of backtracking lifts the LL(1) restriction usually imposed by top-down parsers. In addition, PEG can define parsers with integrated lexing. Unlike some existing parser generators for PEG, the tool does not produce a complex and storage-hungry "packrat parser", but a collection of transparent recursive procedures. ...

...Animations can be generated on the fly based on user input - for a large selection of algorithms and topic areas, including, but not limited to, the topic areas of backtracking algorithms, compression, cryptography, basing, searching and sorting.

The subgraph matching problem (subgraph isomorphism) is NP-complete. Previously, we designed an exact subgraph matching (ESM) algorithm for dependency graphs using a backtracking approach (http://esmalgorithm.sourceforge.net). We further designed an approximate subgraph matching (ASM) algorithm that is capable of detecting approximate subgraph matching based on a subgraph distance. Assume that the graph G and the subgraph Gs have m and n vertices, and km and kn edges respectively, the total worst-case algorithm complexity is O(m^n * n(n-1)/2 * km * log m). ...

The subgraph matching problem (subgraph isomorphism) is NP-complete. We designed a simple exact subgraph matching (ESM) algorithm for dependency graphs using a backtracking approach. The total worst-case algorithm complexity is O(n^2 * k^n) where n is the number of vertices and k is the vertex degree. We have demonstrated the successful usage of our algorithm in three biomedical relation and event extraction applications: BioNLP 2011 shared tasks on event extraction, Protein-Residue association detection and Protein-Protein interaction identification. ...

The LALR parser generator (LPG) is a tool for developing scanners and parsers written in Java, C++ or C. Input is specified by BNF rules. LPG supports backtracking (to resolve ambiguity), automatic AST generation and grammar inheritance.