CS Colloquium: Tom Reps: Context-Free-Language Ordered Binary Decision Diagrams

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Kemper 1131

Thomas Reps

University of Wisconsin-Madison

What could symbolic model checking, path profiling, and quantum simulation

possibly have in common?

CFLOBDDs are a data structure that is essentially plug-compatible with

Binary Decision Diagrams (BDDs), and hence useful for representing

certain classes of functions, relations, matrices, graphs, etc. in a

highly compressed fashion. CFLOBDDs share many of the good properties

of BDDs, but -- in the best case -- the CFLOBDD for a function can be

exponentially smaller than any BDD for that function. Compared with

the size of the decision tree for a function, a CFLOBDD -- again, in

the best case -- can give a double-exponential reduction in size.

 

CFLOBDDs have the potential to permit applications to (i) execute much

faster, and (ii) handle much larger problem instances than has been

possible heretofore. However, CFLOBDDs have certain additional

overheads compared with BDDs, so they are only better than BDDs for

representing very large relations. The successful application area we

found is quantum simulation, where the matrices that need to be

represented are huge.

 

Where does path profiling fit into the story? Come to this talk to

find out!

 

Joint work with Meghana Aparna Sistla (UT-Austin) and Swarat Chaudhuri

(UT-Austin).

 

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Biographical Sketch:

 

Thomas W. Reps is the J. Barkley Rosser Professor & Rajiv and Ritu

Batra Chair in the Computer Sciences Department of the University of

Wisconsin, which he joined in 1985. Reps is the author or co-author

of four books and more than two hundred thirty papers describing

his research. His work has concerned a wide variety of topics,

including program slicing, dataflow analysis, pointer analysis, model

checking, computer security, code instrumentation, language-based

program-development environments, the use of program profiling in

software testing, software renovation, incremental algorithms, and

attribute grammars.

 

Professor Reps received his Ph.D. in Computer Science from Cornell

University in 1982. His Ph.D. dissertation won the 1983 ACM Doctoral

Dissertation Award.

 

Reps has also been the recipient of an NSF Presidential Young

Investigator Award (1986), a Packard Fellowship (1988), a Humboldt

Research Award (2000), and a Guggenheim Fellowship (2000). He is also

an ACM Fellow (2005). In 2013, Reps was elected a foreign member of

Academia Europaea. Reps received the ACM SIGPLAN Programming Languages

Achievement Award for 2017. With A. Lal, M. Musuvathi, S. Qadeer, and

J. Rehof, Reps received the 2023 CAV Award for the ``introduction of

context-bounded analysis and its application to systematic testing of

concurrent programs.''

 

Reps has held visiting positions at the Institut National de Recherche

en Informatique et en Automatique (INRIA) in Rocquencourt, France

(1982-83), the University of Copenhagen, Denmark (1993-94), the

Consiglio Nazionale delle Ricerche in Pisa, Italy (2000-2001), and the

University Paris Diderot-Paris 7 (2007-2008). From 1988 to 2019, he

was President of GrammaTech, Inc.

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