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original version by: Nikos Drakos, CBLU, University of Leeds* revised and updated by: Marcus Hennecke, Ross Moore, Herb Swan* with significant contributions from: Jens Lippmann, Marek Rouchal, Martin Wilck and others --><HTML><HEAD><TITLE>Introduction</TITLE><META NAME="description" CONTENT="Introduction"><META NAME="keywords" CONTENT="cuddIntro"><META NAME="resource-type" CONTENT="document"><META NAME="distribution" CONTENT="global">
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<H1><A NAME="SECTION00010000000000000000"></A><A NAME="sec:intro"></A><BR>Introduction</H1>
<P>The CUDD package provides functions to manipulate Binary DecisionDiagrams<A NAME="14"></A> (BDDs) [<A HREF="node7.html#BDD">5</A>,<A HREF="node7.html#BBR">3</A>],Algebraic Decision Diagrams<A NAME="16"></A> (ADDs)[<A HREF="node7.html#Bahar93">1</A>], and Zero-suppressed Binary DecisionDiagrams<A NAME="18"></A> (ZDDs)[<A HREF="node7.html#Minato93">12</A>]. BDDs are used to representswitching<A NAME="20"></A> functions; ADDs are used torepresent function from <IMG WIDTH="56" HEIGHT="35" ALIGN="MIDDLE" BORDER="0" SRC="img3.png" ALT="$\{0,1\}^n$"> to an arbitrary set. ZDDsrepresent switching<A NAME="21"></A> functions like BDDs;however, they are much more efficient than BDDs when the functions tobe represented are characteristic<A NAME="22"></A>functions of cube<A NAME="23"></A> sets, or in general, when theON-set<A NAME="24"></A> of the function to be represented isvery sparse. They are inferior to BDDs in other cases.
<P>The package provides a large set of operations on BDDs, ADDs, andZDDs, functions to convert BDDs into ADDs or ZDDs and vice versa, anda large assortment of variable reordering<A NAME="25"></A> methods.
<P>The CUDD package can be used in three ways:
<UL><LI>As a black box<A NAME="27"></A>. In this case, the application program that needs to manipulate decision diagrams only uses the exported functions of the package. The rich set of functions included in the CUDD package allows many applications to be written in this way. Section <A HREF="node3.html#sec:user">3</A> describes how to use the exported functions of the package. An application written in terms of the exported functions of the package needs not concern itself with the details of variable reordering<A NAME="29"></A>, which may take place behind the scenes.Click <A NAME="tex2html1" HREF="cuddExtAbs.html">here</A>for a list of the exported functions.</LI><LI>As a clear box<A NAME="32"></A>. When writing a sophisticated application based on decision diagrams, efficiency often dictates that some functions be implemented as direct recursive manipulation of the diagrams, instead of being written in terms of existing primitive functions. Section <A HREF="node4.html#sec:prog">4</A> explains how to add new functions to the CUDD package. It also details how to write a recursive function that can be interrupted by dynamic<A NAME="34"></A> variable reordering.Click <A NAME="tex2html2" HREF="cuddAllAbs.html">here</A>for a list of the exported and internal functions.</LI><LI>Through an interface. Object-oriented languages like C++ and Perl5 can free the programmer from the burden of memory management. A C++ interface is included in the distribution of CUDD. It automatically frees decision diagrams that are no longer used by the application and overloads operators. Almost all the functionality provided by the CUDD exported functions is available through the C++ interface, which is especially recommended for fast prototyping. Section <A HREF="node5.html#sec:cpp">5</A> explains how to use the interface. A Perl5 interface also exists and is ditributed separately. (See Section <A HREF="node2.html#sec:getFriends">2.2</A>.) Some applications define their own interfaces. See for example Section <A HREF="node3.html#sec:sis-vis">3.18</A>.</LI></UL>In the following, the reader is supposed to be familiar with the basicideas about decision diagrams, as found, for instance, in [<A HREF="node7.html#BBR">3</A>].
<P><HR><!--Navigation Panel--><A NAME="tex2html86" HREF="node2.html"><IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="icons/next.png"></A> <A NAME="tex2html82" HREF="cuddIntro.html"><IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="icons/up.png"></A> <A NAME="tex2html76" HREF="cuddIntro.html"><IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="icons/prev.png"></A> <A NAME="tex2html84" HREF="node8.html"><IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="icons/index.png"></A> <BR><B> Next:</B> <A NAME="tex2html87" HREF="node2.html">How to Get CUDD</A><B> Up:</B> <A NAME="tex2html83" HREF="cuddIntro.html">CUDD: CU Decision Diagram</A><B> Previous:</B> <A NAME="tex2html77" HREF="cuddIntro.html">CUDD: CU Decision Diagram</A> <B> <A NAME="tex2html85" HREF="node8.html">Index</A></B> <!--End of Navigation Panel--><ADDRESS>Fabio Somenzi2012-02-04</ADDRESS></BODY></HTML>
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