2003

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• Andreas Hett, Tobias Schubert
  A Hardware Lab in a Pocket
  2003 World Conf. on E-Learning in Corporate, Government, Healthcare, and Higher Education
• Tobias Schubert, Andreas Hett
  A Hardware Lab in a Pocket
  2003 Int'l Conf. on Multimedia and Information and Communication Technologies in Education

2001

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• Wolfgang Günther, Andreas Hett, Bernd Becker
  Application of Linearly Transformed BDDs in Sequential Verification
  2001 ASP Design Automation Conf., Seiten: 91 - 96
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  Kurzfassung

  The computation of the set of reachable states is the key problem of many applications in sequential verification. Binary Decision Diagrams (BDDs) are extensively used in this domain, but tend to blow up for larger instances. To increase the computational power of BDDs, linearly transformed BDDs (LTBDDs) have been proposed. In this paper we show how this concept can be incorporated into the sequential verification domain by restricting dynamic reordering in a way that the relational product can still be carried out efficiently. Experimental results are given to show the efficiency of our approach.
• Andreas Hett, Bernd Becker
  Supervised Dynamic Reordering in Model Checking
  2001 GI/ITG/GMM Workshop “Methoden und Beschreibungssprachen zur Modellierung und Verifikation von Schaltungen und Systemen”, Seiten: 21 - 30

2000

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• Andreas Hett, Christoph Scholl, Bernd Becker
  Distance Driven Finite State Machine Traversal
  2000 IEEE Design Automation Conference, Seiten: 39 - 42
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  Kurzfassung

  Symbolic techniques have revolutionized reachability analysis in the last years. Extending their applicability to handle large, industrial designs is a key issue, involving the need to focus on memory consumption for BDD representation as well as time consumption to perform symbolic traversals of Finite State Machines (FSMs). We address the problem of reachability analysis for large FSMs, introducing a novel technique that performs reachability analysis using a sequence of "distance driven" partial traversals based on dynamically chosen prunings of the transition relation. Experiments are given to demonstrate the efficiency and robustness of our approach: We succeed in completing reachability problems with significantly smaller memory requirements and improved time performance.
• Andreas Hett, Christoph Scholl, Bernd Becker
  State Traversal guided by Hamming Distance Profiles
  2000 GI/ITG/GMM Workshop “Methoden und Beschreibungssprachen zur Modellierung und Verifikation von Schaltungen und Systemen”, VDE Verlag, Seiten: 57 - 66

1999

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• Andreas Hett, Christoph Scholl, Bernd Becker
  A.MORE - A Multi-Operand BDD Package
  University of Freiburg, 1999
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  Kurzfassung

  Decision Diagrams (DDs) are often used in CAD systems for the efficient representation and manipulation of Boolean functions. The most popular data structure in this context are Ordered Binary Decision Diagrams (OBDDs) that are used in many applications. This package provides a novel approach for synthesizing BDDs using operator nodes instead of procedure calls. Thus, transformations on this data structure are possible as well as the flexibility to adapt the synthesis process in order to execute the 'most primising paths' first, resulting in less superfluous calculations and lower memory usage due to the skipping of unneeded branches.
• Andreas Hett
  MORE good BDD Ideas
  1999 Dagstuhl Seminar on Computer Aided Design and Test, Decision Diagrams: Concepts and Applications

1997

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• Andreas Hett, Rolf Drechsler, Bernd Becker
  Fast and Efficient Construction of BDDs by reordering based Synthesis
  1997 European Design and Test Conf., Seiten: 168 - 175
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  Kurzfassung

  We present a new approach to symbolic simulation with BDDs. Our method uses Reordering Based Synthesis (RBS) whichallows the integration of dynamic variable ordering (even) within a single synthesis operation (e.g. an AND-operation). Thus huge peak sizes during the construction often can be avoided, and we obtain a method that, with no penalty in runtime, is more memory efficient than traditional ITE operator based symbolic simulation. The results are confirmed by experiments on a large set of benchmarks: We give a comparison to several previously published approaches and also consider some industrial benchmarks which are known to be hard to handle.
• Andreas Hett, Rolf Drechsler, Bernd Becker
  Reordering Based Synthesis
  1997 iwrm
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  Kurzfassung

  Reordering Based Synthesis (RBS) as an alternative approach to manipulate Decision Diagrams (DDs) is presented. Based on the concept of operation nodes a single "core" operation, i.e. an extended Level Exchange (LE), is sufficient to perform the usual synthesis operations on several types of DDs. RBS allows the integration of dynamic variable ordering (even) within a single synthesis operation (e.g. an AND-operation) and thus provides the possibility of avoiding huge peak sizes during the construction. The optimization potential is significantly enlarged by allowing LEs even between operation nodes. A large number of experimental results for the

1996

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• Rolf Drechsler, Andreas Hett, Bernd Becker
  A Note on Symbolic Simulation using Desicion Diagrams
  1996 ulsi
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  Kurzfassung

  If Decision Diagrams (DDs) are used for the representation of the logical behaviour of a combinational logic circuit it has to be traversed in topological order. At each gate the corresponding synthesis operation is carried out. This traversal process is called symbolic simulation. Obviously the sequence in which the operations are performed at each gate influences the number of nodes needed during the computation. In this paper we consider different traversal strategies for OBDDs and OMDDs. We compare them by means of experiments.
• Andreas Hett, Rolf Drechsler, Bernd Becker
  MORE Optimization Techniques.
  , 1996
• Andreas Hett, Rolf Drechsler, Bernd Becker
  The DD Package PUMA - An Online Documentation
  https://ira.informatik.uni-freiburg.de/software/puma/, 1996
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  Kurzfassung

  PUMA is a DD-Package for the efficient representation and manipulation of Boolean Functions with OKFDDs as well as Zero-Suppressed BDDs.