# Jeffrey O. Shallit

According to our database1, Jeffrey O. Shallit authored at least 254 papers between 1984 and 2021.

Collaborative distances:
• Dijkstra number2 of four.
• Erdős number3 of two.

Book
In proceedings
Article
PhD thesis
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## Bibliography

2021
Ostrowski-automatic sequences: Theory and applications.
Theor. Comput. Sci., 2021

Robbins and Ardila meet Berstel.
Inf. Process. Lett., 2021

Borders, palindrome prefixes, and square prefixes.
Inf. Process. Lett., 2021

Avoidance of split overlaps.
Discret. Math., 2021

Frobenius Numbers and Automatic Sequences.
CoRR, 2021

Decidability for Sturmian words.
CoRR, 2021

Lie complexity of words.
CoRR, 2021

Computational Fun with Sturdy and Flimsy Numbers.
Proceedings of the 10th International Conference on Fun with Algorithms, 2021

2020
Unique decipherability in formal languages.
Theor. Comput. Sci., 2020

Additive Number Theory via Automata Theory.
Theory Comput. Syst., 2020

Lengths of words accepted by nondeterministic finite automata.
Inf. Process. Lett., 2020

New bounds on antipowers in words.
Inf. Process. Lett., 2020

Additive Number Theory via Approximation by Regular Languages.
Int. J. Found. Comput. Sci., 2020

Sum-free sets generated by the period-k-folding sequences and some Sturmian sequences.
Discret. Math., 2020

String Attractors for Automatic Sequences.
CoRR, 2020

Abelian Complexity and Synchronization.
CoRR, 2020

Subword complexity of the Fibonacci-Thue-Morse sequence: the proof of Dekking's conjecture.
CoRR, 2020

The Largest Entry in the Inverse of a Vandermonde Matrix.
CoRR, 2020

The Simplest Binary Word with Only Three Squares.
CoRR, 2020

Extremal overlap-free and extremal β-free binary words.
CoRR, 2020

Sumsets of Wythoff Sequences, Fibonacci Representation, and Beyond.
CoRR, 2020

An inequality for the number of periods in a word.
CoRR, 2020

A Frameless 2-Coloring of the Plane Lattice.
CoRR, 2020

Decidability and k-Regular Sequences.
CoRR, 2020

Computational Aspects of Sturdy and Flimsy Numbers.
CoRR, 2020

Avoidance of split overlaps.
CoRR, 2020

Extremal Overlap-Free and Extremal $\beta$-Free Binary Words.
Electron. J. Comb., 2020

Queens in Exile: Non-attacking Queens on Infinite Chess Boards.
Electron. J. Comb., 2020

Existential Length Universality.
Proceedings of the 37th International Symposium on Theoretical Aspects of Computer Science, 2020

The State Complexity of Lexicographically Smallest Words and Computing Successors.
Proceedings of the Developments in Language Theory - 24th International Conference, 2020

2019
Subword complexity and power avoidance.
Theor. Comput. Sci., 2019

Critical exponents of infinite balanced words.
Theor. Comput. Sci., 2019

The number of valid factorizations of Fibonacci prefixes.
Theor. Comput. Sci., 2019

Rollercoasters: Long Sequences without Short Runs.
SIAM J. Discret. Math., 2019

Circular critical exponents for Thue-Morse factors.
RAIRO Theor. Informatics Appl., 2019

Cobham's Theorem and Automaticity.
Int. J. Found. Comput. Sci., 2019

The Generalized Nagell-Ljunggren Problem: Powers with Repetitive Representations.
Exp. Math., 2019

New Bounds on Antipowers in Binary Words.
CoRR, 2019

Words With Few Palindromes, Revisited.
CoRR, 2019

Words Avoiding Reversed Factors, Revisited.
CoRR, 2019

Automatic sequences are also non-uniformly morphic.
CoRR, 2019

Continuants, Run Lengths, and Barry's Modified Pascal Triangle.
Electron. J. Comb., 2019

Waring's Theorem for Binary Powers.
Comb., 2019

Optimal Regular Expressions for Permutations.
Proceedings of the 46th International Colloquium on Automata, Languages, and Programming, 2019

Generalized de Bruijn Words and the State Complexity of Conjugate Sets.
Proceedings of the Descriptional Complexity of Formal Systems, 2019

New Results on Pseudosquare Avoidance.
Proceedings of the Combinatorics on Words - 12th International Conference, 2019

Circularly Squarefree Words and Unbordered Conjugates: A New Approach.
Proceedings of the Combinatorics on Words - 12th International Conference, 2019

Repetitions in Infinite Palindrome-Rich Words.
Proceedings of the Combinatorics on Words - 12th International Conference, 2019

Critical Exponent of Infinite Balanced Words via the Pell Number System.
Proceedings of the Combinatorics on Words - 12th International Conference, 2019

2018
Preface.
Inf. Comput., 2018

Common factors in automatic and Sturmian sequences.
CoRR, 2018

Sums of Palindromes: an Approach via Automata.
Proceedings of the 35th Symposium on Theoretical Aspects of Computer Science, 2018

Lagrange's Theorem for Binary Squares.
Proceedings of the 43rd International Symposium on Mathematical Foundations of Computer Science, 2018

Rollercoasters and Caterpillars.
Proceedings of the 45th International Colloquium on Automata, Languages, and Programming, 2018

Counting Subwords and Regular Languages.
Proceedings of the Developments in Language Theory - 22nd International Conference, 2018

2017
Abelian-square-rich words.
Theor. Comput. Sci., 2017

Decision algorithms for Fibonacci-automatic words, II: Related sequences and avoidability.
Theor. Comput. Sci., 2017

Preface.
J. Autom. Lang. Comb., 2017

Periodicity in rectangular arrays.
Inf. Process. Lett., 2017

A Taxonomy of Morphic Sequences.
CoRR, 2017

Disjoint covering systems and the reversion of the Möbius series.
CoRR, 2017

When is an automatic set an additive basis?
CoRR, 2017

Sums of Palindromes: an Approach via Nested-Word Automata.
CoRR, 2017

A Class of Exponential Sequences with Shift-Invariant Discriminators.
CoRR, 2017

Existential length universality.
CoRR, 2017

Fractional Coverings, Greedy Coverings, and Rectifier Networks.
Proceedings of the 34th Symposium on Theoretical Aspects of Computer Science, 2017

Undecidability and Finite Automata.
Proceedings of the Developments in Language Theory - 21st International Conference, 2017

Overpals, Underlaps, and Underpals.
Proceedings of the Combinatorics on Words - 11th International Conference, 2017

2016
Decision algorithms for Fibonacci-automatic Words, I: Basic results.
RAIRO Theor. Informatics Appl., 2016

Palindromic rich words and run-length encodings.
Inf. Process. Lett., 2016

Discriminators and k-Regular Sequences.
Integers, 2016

Remarks on Privileged Words.
Int. J. Found. Comput. Sci., 2016

Decision Algorithms for Fibonacci-Automatic Words, III: Enumeration and Abelian Properties.
Int. J. Found. Comput. Sci., 2016

Minimal Elements for the Prime Numbers.
Exp. Math., 2016

Periodicity in Rectangular Arrays.
CoRR, 2016

Minimum Critical Exponents for Palindromes.
CoRR, 2016

Length of the continued logarithm algorithm on rational inputs.
CoRR, 2016

On the subword complexity of the fixed point of $a \rightarrow aab$, $b \rightarrow b$, and generalizations.
CoRR, 2016

Closed, Palindromic, Rich, Privileged, Trapezoidal, and Balanced Words in Automatic Sequences.
Electron. J. Comb., 2016

Periods and Borders of Random Words.
Proceedings of the 33rd Symposium on Theoretical Aspects of Computer Science, 2016

2015
Automatic Sets of Rational Numbers.
Int. J. Found. Comput. Sci., 2015

Optimal Bounds for the Similarity Density of the Thue-Morse Word with Overlap-Free and 73-Power-Free Infinite Binary Words.
Int. J. Found. Comput. Sci., 2015

Closed, Rich, Privileged, Trapezoidal, and Balanced Words in Automatic Sequences.
CoRR, 2015

On the Combinatorics of Palindromes and Antipalindromes.
CoRR, 2015

Hankel Matrices for the Period-Doubling Sequence.
CoRR, 2015

Factorization in Formal Languages.
Proceedings of the Developments in Language Theory - 19th International Conference, 2015

Mechanical Proofs of Properties of the Tribonacci Word.
Proceedings of the Combinatorics on Words - 10th International Conference, 2015

A New Approach to the Paperfolding Sequences.
Proceedings of the Evolving Computability - 11th Conference on Computability in Europe, 2015

2014
Avoiding Three Consecutive Blocks of the Same Size and Same Sum.
J. ACM, 2014

Reviewing the Early Days of Computing [Book Review].
Comput. Sci. Eng., 2014

Similarity density of the Thue-Morse word with overlap-free infinite binary words.
Proceedings of the Proceedings 14th International Conference on Automata and Formal Languages, 2014

Decision Algorithms for Fibonacci-Automatic Words, with Applications to Pattern Avoidance.
CoRR, 2014

Notes and Note-Pairs in Noergaard's Infinity Series.
CoRR, 2014

Counting the Palstars.
Electron. J. Comb., 2014

2013
Review of computability and complexity theory by Steven Homer and Alan L. Selman.
SIGACT News, 2013

Automatic Theorem-Proving in Combinatorics on Words.
Int. J. Found. Comput. Sci., 2013

Composition and orbits of language operations: finiteness and upper bounds.
Int. J. Comput. Math., 2013

Filtrations of Formal Languages by Arithmetic Progressions.
Fundam. Informaticae, 2013

Counting Sequences with Small Discrepancies.
Exp. Math., 2013

Counting Palstars.
CoRR, 2013

Remarks on Privileged Words.
CoRR, 2013

Primitive Words and Lyndon Words in Automatic and Linearly Recurrent Sequences.
Proceedings of the Language and Automata Theory and Applications, 2013

On the Number of Unbordered Factors.
Proceedings of the Language and Automata Theory and Applications, 2013

Repetition Avoidance in Circular Factors.
Proceedings of the Developments in Language Theory - 17th International Conference, 2013

Subword Complexity and k-Synchronization.
Proceedings of the Developments in Language Theory - 17th International Conference, 2013

Shortest Repetition-Free Words Accepted by Automata.
Proceedings of the Descriptional Complexity of Formal Systems, 2013

Sets Represented as the Length-n Factors of a Word.
Proceedings of the Combinatorics on Words - 9th International Conference, 2013

Decidability and Enumeration for Automatic Sequences: A Survey.
Proceedings of the Computer Science - Theory and Applications, 2013

Description of Generalized Continued Fractions by Finite Automata.
Proceedings of the Number Theory and Related Fields, In Memory of Alf van der Poorten, 2013

2012
Review of biscuits of number theory by Arthur T. Benjamin and Ezra Brown.
SIGACT News, 2012

Review of finite fields and applications by Gary L. Mullen and Carl Mummert.
SIGACT News, 2012

The Critical Exponent is Computable for Automatic Sequences.
Int. J. Found. Comput. Sci., 2012

Enumeration and Decidable Properties of Automatic Sequences.
Int. J. Found. Comput. Sci., 2012

The Computational Complexity of Universality Problems for Prefixes, Suffixes, Factors, and Subwords of Regular Languages.
Fundam. Informaticae, 2012

Shuffling and Unshuffling.
Bull. EATCS, 2012

Avoiding 3/2-powers over the natural numbers.
Discret. Math., 2012

Sturmian graphs and integer representations over numeration systems.
Discret. Appl. Math., 2012

Least periods of k-automatic sequences
CoRR, 2012

Primitive Words and Lyndon Words in Automatic Sequences
CoRR, 2012

The Subword Complexity of k-Automatic Sequences is k-Synchronized
CoRR, 2012

Enumerating regular expressions and their languages
CoRR, 2012

Automatic Theorem-Proving in Combinatorics on Words
CoRR, 2012

k-Automatic Sets of Rational Numbers.
Proceedings of the Language and Automata Theory and Applications, 2012

The State Complexity of Star-Complement-Star.
Proceedings of the Developments in Language Theory - 16th International Conference, 2012

2011
Information theory, evolutionary computation, and Dembski's "complex specified information".
Synth., 2011

Inverse star, borders, and palstars.
Inf. Process. Lett., 2011

Unbounded Discrepancy in Frobenius Numbers.
Integers, 2011

Van der Waerden's Theorem and Avoidability in Words.
Integers, 2011

Closures in Formal Languages and Kuratowski's Theorem.
Int. J. Found. Comput. Sci., 2011

Decision problems for convex languages.
Inf. Comput., 2011

A pattern sequence approach to Stern's sequence.
Discret. Math., 2011

Shuffling and Unshuffling
CoRR, 2011

Fife's Theorem for (7/3)-Powers
Proceedings of the Proceedings 8th International Conference Words 2011, 2011

The Critical Exponent is Computable for Automatic Sequences
Proceedings of the Proceedings 8th International Conference Words 2011, 2011

A variant of Hofstadter's sequence and finite automata
CoRR, 2011

Finite Orbits of Language Operations.
Proceedings of the Language and Automata Theory and Applications, 2011

Fife's Theorem Revisited.
Proceedings of the Developments in Language Theory - 15th International Conference, 2011

Remarks on Separating Words.
Proceedings of the Descriptional Complexity of Formal Systems, 2011

Decidability and Shortest Strings in Formal Languages.
Proceedings of the Descriptional Complexity of Formal Systems, 2011

2010
Cryptographic applications of analytic number theory: lower bounds and pseudorandomness author of book: Igor Shparlinski Birkäuser, 2003.
SIGACT News, 2010

Detecting patterns in finite regular and context-free languages.
Inf. Process. Lett., 2010

Finding the Growth Rate of a Regular or Context-Free Language in Polynomial Time.
Int. J. Found. Comput. Sci., 2010

On Lazy Representations and Sturmian Graphs.
Proceedings of the Implementation and Application of Automata, 2010

2009
State complexity of unique rational operations.
Theor. Comput. Sci., 2009

Decimations of languages and state complexity.
Theor. Comput. Sci., 2009

On NFAs where all states are final, initial, or both.
Theor. Comput. Sci., 2009

Periodicity, repetitions, and orbits of an automatic sequence.
Theor. Comput. Sci., 2009

Efficient enumeration of words in regular languages.
Theor. Comput. Sci., 2009

Detecting palindromes, patterns and borders in regular languages.
Inf. Comput., 2009

Hamming distance for conjugates.
Discret. Math., 2009

Avoiding squares and overlaps over the natural numbers.
Discret. Math., 2009

Automata and Reduced Words in the Free Group
CoRR, 2009

Length of the Shortest Word in the Intersection of Regular Languages
CoRR, 2009

Closures in Formal Languages: Concatenation, Separation, and Algorithms
CoRR, 2009

Counting Abelian Squares.
Electron. J. Comb., 2009

2008
Words avoiding repetitions in arithmetic progressions.
Theor. Comput. Sci., 2008

Avoiding Approximate Squares.
Int. J. Found. Comput. Sci., 2008

On NFAs Where All States are Final, Initial, or Both
CoRR, 2008

An NP-hardness Result on the Monoid Frobenius Problem
CoRR, 2008

Bounds for the discrete correlation of infinite sequences on k symbols and generalized Rudin-Shapiro sequences.
CoRR, 2008

Morphic and Automatic Words: Maximal Blocks and Diophantine Approximation.
CoRR, 2008

The Frobenius Problem in a Free Monoid.
Proceedings of the STACS 2008, 2008

Finite Automata, Palindromes, Powers, and Patterns.
Proceedings of the Language and Automata Theory and Applications, 2008

The Frobenius Problem and Its Generalizations.
Proceedings of the Developments in Language Theory, 12th International Conference, 2008

Finding the Growth Rate of a Regular of Context-Free Language in Polynomial Time.
Proceedings of the Developments in Language Theory, 12th International Conference, 2008

A Second Course in Formal Languages and Automata Theory.
Cambridge University Press, ISBN: 978-0-521-86572-2, 2008

2007
Every real number greater than 1 is a critical exponent.
Theor. Comput. Sci., 2007

Enumeration of Context-Free Languages and Related Structures.
J. Autom. Lang. Comb., 2007

On Sturmian graphs.
Discret. Appl. Math., 2007

Finding the growth rate of a regular language in polynomial time
CoRR, 2007

Finite automata, palindromes, patterns, and borders
CoRR, 2007

Efficient Enumeration of Regular Languages.
Proceedings of the Implementation and Application of Automata, 2007

Avoiding Approximate Squares.
Proceedings of the Developments in Language Theory, 11th International Conference, 2007

2006
Squares and overlaps in the Thue-Morse sequence and some variants.
RAIRO Theor. Informatics Appl., 2006

Binary Words Containing Infinitely Many Overlaps.
Electron. J. Comb., 2006

New Directions in State Complexity.
Proceedings of the 8th International Workshop on Descriptional Complexity of Formal Systems - DCFS 2006, Las Cruces, New Mexico, USA, June 21, 2006

2005
Avoiding large squares in infinite binary words.
Theor. Comput. Sci., 2005

A generalization of repetition threshold.
Theor. Comput. Sci., 2005

Regular Expressions: New Results and Open Problems.
J. Autom. Lang. Comb., 2005

State complexity and the monoid of transformations of a finite set.
Int. J. Found. Comput. Sci., 2005

Non-uniqueness and radius of cyclic unary NFAs.
Int. J. Found. Comput. Sci., 2005

Self-generating sets, integers with missing blocks, and substitutions.
Discret. Math., 2005

2004
Polynomial versus exponential growth in repetition-free binary words.
J. Comb. Theory, Ser. A, 2004

Simultaneous Avoidance Of Large Squares And Fractional Powers In Infinite Binary Words.
Int. J. Found. Comput. Sci., 2004

On the iteration of certain quadratic maps over GF(<i>p</i>).
Discret. Math., 2004

Enumerating Regular Expressions and Their Languages.
Proceedings of the Implementation and Application of Automata, 2004

Sturmian Graphs and a Conjecture of Moser.
Proceedings of the Developments in Language Theory, 2004

2003
Periodicity, morphisms, and matrices.
Theor. Comput. Sci., 2003

The ring of k-regular sequences, II.
Theor. Comput. Sci., 2003

A Generalization of Repetition Threshold
CoRR, 2003

Cubefree binary words avoiding long squares
CoRR, 2003

Automatic Sequences - Theory, Applications, Generalizations.
Cambridge University Press, ISBN: 978-0-521-82332-6, 2003

2002
On two-sided infinite fixed points of morphisms.
Theor. Comput. Sci., 2002

The computational complexity of the local postage stamp problem.
SIGACT News, 2002

Unary Context-Free Grammars and Pushdown Automata, Descriptional Complexity and Auxiliary Space Lower Bounds.
J. Comput. Syst. Sci., 2002

On the Number of Distinct Languages Accepted by Finite Automata with n States.
J. Autom. Lang. Comb., 2002

Simulating finite automata with context-free grammars.
Inf. Process. Lett., 2002

Unary Language Operations, State Complexity and Jacobsthal's Function.
Int. J. Found. Comput. Sci., 2002

The Cycles of the Multiway Perfect Shuffle Permutation.
Discret. Math. Theor. Comput. Sci., 2002

Regular Expressions: New Results and Open Problems.
Proceedings of the Fourth International Workshop on Descriptional Complexity of Formal Systems - DCFS 2002, London, Canada, August 21, 2002

2001
Automatic Complexity of Strings.
J. Autom. Lang. Comb., 2001

Weakly Self-Avoiding Words and a Construction of Friedman.
Electron. J. Comb., 2001

Variations on a Theorem of Fine & Wilf.
Proceedings of the Mathematical Foundations of Computer Science 2001, 2001

Minimal Covers of Formal Languages.
Proceedings of the Developments in Language Theory, 5th International Conference, 2001

2000
A Recurrence Generating Multiples of Primes: 10655.
Am. Math. Mon., 2000

Automaticity and Rationality.
J. Autom. Lang. Comb., 2000

Sums of Digits, Overlaps, and Palindromes.
Discret. Math. Theor. Comput. Sci., 2000

State Complexity and Jacobsthal's Function.
Proceedings of the Implementation and Application of Automata, 2000

Formal languages and number theory.
Proceedings of the Unusual Applications of Number Theory, 2000

1999
Number Theory.
Proceedings of the Handbook of Discrete and Combinatorial Mathematics., 1999

The Computational Complexity of Some Problems of Linear Algebra.
J. Comput. Syst. Sci., 1999

Separating Words with Small Grammars.
J. Autom. Lang. Comb., 1999

An Efficient Algorithm for Computing the <i>i</i>th letter of 4<sup>n</sup>a.
Proceedings of the Tenth Annual ACM-SIAM Symposium on Discrete Algorithms, 1999

New problems of pattern avoidance.
Proceedings of the Developments in Language Theory, 1999

1998
Generalized Perturbed Symmetry.
Eur. J. Comb., 1998

On Minimal Words With Given Subword Complexity.
Electron. J. Comb., 1998

Extremal Infinite Overlap-Free Binary Words.
Electron. J. Comb., 1998

Automaticity III: Polynomial Automaticity and Context-Free Languages.
Comput. Complex., 1998

The Ubiquitous Prouhet-Thue-Morse Sequence.
Proceedings of the Sequences and their Applications, 1998

1997
Social Issues in Canada's Information Society.
Inf. Soc., 1997

Automaticity II: Descriptional Complexity in the Unary Case.
Theor. Comput. Sci., 1997

Automatic Maps in Exotic Numeration System.
Theory Comput. Syst., 1997

The Computational Complexity of Some Problems of Linear Algebra (Extended Abstract).
Proceedings of the STACS 97, 14th Annual Symposium on Theoretical Aspects of Computer Science, Lübeck, Germany, February 27, 1997

1996
On the Vector Space of the Automatic Reals.
Theor. Comput. Sci., 1996

Results and estimates on pseudopowers.
Math. Comput., 1996

Automaticity I: Properties of a Measure of Descriptional Complexity.
J. Comput. Syst. Sci., 1996

A Lower Bound Technique for the Size of Nondeterministic Finite Automata.
Inf. Process. Lett., 1996

Polynomial Automaticity, Context-Free Languages, and Fixed Points of Morphism (Extended Abstract).
Proceedings of the Mathematical Foundations of Computer Science 1996, 1996

1995
Subword Complexity of a Generalized Thue-Morse Word.
Inf. Process. Lett., 1995

1994
Numeration Systems, Linear Recurrences, and Regular Sets
Inf. Comput., September, 1994

A Minimization Problem.
SIAM Rev., 1994

Analysis of a Left-Shift Binary GCD Algorithm.
J. Symb. Comput., 1994

on Sparse Languages L such that LL = Sigma.
Discret. Appl. Math., 1994

Automaticity: Properties of a Measure of Descriptional Complexity.
Proceedings of the STACS 94, 1994

1993
Factor Refinement.
J. Algorithms, 1993

On the maximum number of distinct factors of a binary string.
Graphs Comb., 1993

A binary algorithm for the Jacobi symbol.
SIGSAM Bull., 1993

1992
The Ring of k-Regular Sequences.
Theor. Comput. Sci., 1992

Pattern Spectra, Substring Enumeration, and Automatic Sequences.
Theor. Comput. Sci., 1992

Randomized algorithms in "primitive" cultures or what is the oracle complexity of a dead chicken?
SIGACT News, 1992

The "3x + 1" Problem and Finite Automata.
Bull. EATCS, 1992

Characterizing Regular Languages with Polynomial Densities.
Proceedings of the Mathematical Foundations of Computer Science 1992, 1992

Numeration Systems, Linear Recurrences, and Regular Sets (Extended Abstract).
Proceedings of the Automata, Languages and Programming, 19th International Colloquium, 1992

1990
On the Worst Case of Three Algorithms for Computing the Jacobi Symbol.
J. Symb. Comput., 1990

1989
Analysis of an Infinite Product Algorithm.
SIAM J. Discret. Math., 1989

Wire bending.
J. Comb. Theory, Ser. A, 1989

Sur Des Points Fixes De Morphismes D'Un Monoïde Libre.
RAIRO Theor. Informatics Appl., 1989

Two methods for generating fractals.
Comput. Graph., 1989

1988
A Generalization of Automatic Sequences.
Theor. Comput. Sci., 1988

A Subset Coloring Algorithm and Its Applications to Computer Graphics.
Commun. ACM, 1988

1986
Sums of Divisors, Perfect Numbers and Factoring.
SIAM J. Comput., 1986

1985
Number-Theoretic Functions Which Are Equivalent to Number of Divisors.
Inf. Process. Lett., 1985

Factoring with Cyclotomic Polynomials
Proceedings of the 26th Annual Symposium on Foundations of Computer Science, 1985

1984
Sums of Divisors, Perfect Numbers, and Factoring (Extended Abstract)
Proceedings of the 16th Annual ACM Symposium on Theory of Computing, April 30, 1984