// CrocoPat is a tool for relational querying.
// This file is part of CrocoPat. 

// Copyright (C) 2002-2005  Dirk Beyer, Andreas Noack


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New features in release 2.1.2, 2005-02-12

- The new numerical expression 'ELAPSED' returns the processor time
  (in seconds) elapsed since the previous interpretation of 'ELAPSED'
  or (in the first interpretation of 'ELAPSED') since the program start.
- The new string expression 'ELEMENT(rel_expr)' returns the lexicographically
  smallest element in the result of rel_expr.  The result of rel_expr
  must be nonempty and rel_expr must have exactly one free attribute.
- Improved performance for the cardinality operator # and 
  the built-in lexicographical order relations (=, <, >, etc).
- Improved performance for regular expression matching.
- Identifiers for relation variables can contain arbitrary characters 
  (except ') if quoted: '...'. In particular useful for processing RDF data.
- Output of BDDs:
  - NODESPERVAR(rel_expr)
    prints the number of nodes
    for each boolean variable in the BDD for rel_expr.
    For BDD shape visualization with VisuBDD (see below).
  - GRAPH(rel_expr)
    prints the graph for the BDD for rel_expr in the GraphViz format.
    For BDD visualization with GraphViz (http://www.graphviz.org/).
  - BDT(rel_expr)
    prints a binary decision tree for the BDD for rel_expr.
- Java program VisuBDD, which visualizes the shape of a BDD,
  using the output of 'PRINT GRAPH(rel_expr)'.