Curriculum Vita

James A. Davis
2214 Grainmill Court
Richmond, VA 23233
(804) 289-8094 (W)
(804) 747-5858 (H)
jdavis@richmond.edu

EDUCATION:

Ph.D. Mathematics, University of Virginia, August, 1987.  Dissertation: "Difference sets in abelian 2-groups";

B.S. Mathematics with Honors, Magna cum laude, Lafayette College, May, 1983.

EMPLOYMENT:
Professor, University of Richmond, 2001-Present.

Associate Professor, University of Richmond, 1994-2001.

Assistant Professor, University of Richmond, 1988-1994.

Visiting Assistant Professor, Lafayette College, August 1987-1988.

Teaching Assistant, University of Virginia, August 1983-1987.

Summer Actuary Intern, Provident Mutual Life Insurance Company, Summer of 1982.

DESCRIPTION OF RESEARCH:
Use of algebraic and number theoretic tools to construct combinatorial structures in Design Theory and Coding
Theory.

PUBLICATIONS OF NOTE:
The following selection of papers illustrates publications of note over the past few years.  A complete list of
publications is included later in the Curriculum Vita.

A Unifying Construction for Difference Sets, with J.Jedwab, Journal of Combinatorial Theory, Series A,
Vol. 80 No.1, 13-78, Oct. 1997.
The following review appeared in Math Reviews MR 98g#05021:

The paper under review clearly ranks as one of the most important papers in the general area of difference sets
ever written. I will just mention the most striking results that make it important: It contains the first new
parameter family of difference sets found since 1977. It gives a unifying theory which allows one to produce a
difference set with $(\nu,n)>1$ in every abelian group which is known to contain such a difference set. Not
only was this true at the time of writing the paper, but it also holds for the new families of difference sets which
were subsequently discovered by Y. Q. Chen [Finite Fields Appl. 3 (1997), no. 3, 234--256 1459826; Des.
Codes Cryptogr. 13 (1998), no. 3, 247--250 1601576]. It characterises a certain class of groups containing
McFarland difference sets. It allows a transparent treatment of the family of Hadamard difference sets, whereas
the best previous description (in terms of binary arrays and binary supplementary quadruples) was still rather
cumbersome. In particular, the celebrated characterization theorem for those abelian 2-groups which contain a
difference set (a problem which took decades to settle) becomes a trivial corollary. It gives a unified way of
constructing semiregular relative difference sets in virtually all the known cases, and it gives many new
examples.
Reviewer: Jungnickel, Dieter (D-AGSB)

Peak-to-mean power control in OFDM, Golay complementary sequences and Reed-Muller codes, with
J.Jedwab, IEEE Transactions on Information Theory, Vol. 45, 2397-2417, 1999.
OFDM is a proposed transmission scheme designed to provide more reliable and quicker communication
between mobile devices. This paper demonstrates that the use of Golay complementary sequences
simultaneously controls the required transmission power and provides efficient error-correcting capabilities
through the use of Reed-Muller codes.  Also addressed in the paper are flexible implementation possibilities
obtained by trading off code rate, power control, and error correction capability.  The problems considered in
this paper arose during my sabbatical year 1995-96 at Hewlett-Packard Laboratories, and it illustrates the
usefulness of theoretical mathematics in answering applied problems in communication engineering. This

paper had more than 500 citations as of June 2012.

Hadamard Difference Sets in Nonabelian 2-Groups, with J.Iiams, Journal of Algebra, 199, 62-87, 1998.
This paper uses representation theory to construct Hadamard difference sets in nonabelian 2-groups.  This
collection of difference sets has the property that the asymptotic value of the exponent is 2^(3t+2) for a group
of order 2^(4t+2).  For abelian groups of order 2^(4t+2), the exponent is bounded by 2^(2t+2), so these
examples clearly demonstrate that nonabelian groups will allow difference sets with very different algebraic
properties than their abelian counterparts.  In addition, this paper provides tools for using representation theory
to identify subsets which will have desirable properties for constructing difference sets.

New Families of Semi-Regular Relative Difference Sets, with J.Jedwab and M.Mowbray, Designs, Codes,
and Cryptography 13, 131-146, 1998.
This paper combines direct product difference sets from projective planes with relative difference sets in
2-groups to construct relative difference sets in larger groups.  These examples include some of the first
examples in the literature of large forbidden subgroup semi-regular relative difference sets in groups whose
order is not a prime power.  Discussing semi-regular relative difference sets in general, A.Pott wrote in "A
survey of relative difference sets", Groups, Difference Sets, and the Monster, (K.T.Arasu et. al., eds.),
195-232, de Gruyter, New York, 1996:  "It is, in my opinion, one of the most interesting questions about
relative difference sets to find all possible groups G which contain such a difference set ..."  This paper is
of interest because the family of combinatorial objects constructed had not even been discovered at the
time Pott wrote his survey.

Constructions of Low Rank Relative Difference Sets in 2-groups Using Galois Rings,  with Q.Xiang, Finite
Fields and their Applications 6, 130-145, 2000.
Galois Rings have been powerful tools over the past few years in constructing designs and codes with good
properties.  This paper demonstrates that Galois Rings can be used to construct relative difference sets in groups
with lower rank than any previous constructions.  The best known previous results required a rank of 2t for a
group of order 2^(3t) and forbidden subgroup of order 2^t, and this paper only requires a rank of (3/2)t for the
same parameters.  In addition, we use results from quadratic forms to compute the exact value for a parameter
in the Galois Ring, and this allows us to determine the exact range of parameters of the partial difference sets in
the Galois Ring constructed by Y.Q.Chen, D.K.Ray-Chaudhuri, and Q.Xiang in "Constructions of partial
difference sets using Galois rings, II", J. Combin.Theory Ser. A, 76, 179-196, 1996.

PRESENTATIONS OF NOTE:
The following selection of presentations illustrates talks of note over the past five years.  A complete list of
presentations is included later in the Curriculum Vita.

A Unifying Construction for Difference Sets, parts 1 and 2, NATO conference on difference sets,
sequences, and their correlation properties, Bad Windsheim, Germany, August 4 & 5, 1998
These two hour-long invited talks were designed to provide an introduction to my joint work
with J. Jedwab.  Approximately 75 experts and students in the audience.

Golay complementary sequences and Reed-Muller codes, NATO conference on difference sets, sequences,
and their correlation properties, Bad Windsheim, Germany, August 6, 1998
This one hour lecture gave an overview of my joint work with J.Jedwab to approximately 75 experts and
students in the audience.

From the Kirkman schoolgirl problem to error correcting codes: different views of difference sets, The
University of Wales at Aberystwyth colloquium, May, 1996.
This colloquium lecture presented topics from several papers, indicating the connections between difference
sets and coding theory.

Denniston Partial Difference Sets, The National University of Singapore, June, 2000.
This seminar talk presented my joint work with Qing Xiang, covering the connections between Hadamard
difference sets, Singer difference sets, and Denniston partial difference sets.

Boolean functions with high second order nonlinearity, Cornel Bodea, 2010.

Crossover property of the nonperiodic autocorrelation function of quaternary sequences, Michael Pohl, 2007.

Relative difference sets in 2-groups: a group cohomological viewpoint, Brian Wyman, 2005.

Difference sets, symmetric designs, and coding theory: a look at the incidence matrices for several difference sets,
Kate Nieswand, 2000.

On some new constructions of difference sets, Sarah Spence, 1997.

Generalizations of the mod4 construction of the Nordstrom-Robinson Code, Tim Frey, 1995.

Topics in cyclotomic and quadratic fields, Pam Mellinger, 1993.

A new view of McFarland difference sets, John Polhill, 1993.

SUMMER RESEARCH PROJECTS DIRECTED:
Boolean functions with high second order nonlinearity, Gavin McGrew, Dayton Steele, Katherine Marsten, Xi He,

Shalleetta Hicks, Taryn Smith, Zach Davis, Timmy Albright, Irina Kiseeva, Kirstin Ladas, Alex Martin, Kate

Pitchford, Summer 2011. Sponsored by the National Science Foundation, the Grainger Foundation, and the

University of Richmond Undergraduate Research Committee.

Boolean functions with high second order nonlinearity, Gavin McGrew, Alex Martin, Kate Pitchford, Katherine Utz,

Francesco Spadaro, Josh Wilson, Taryn Smith, summer 2010. Sponsored by the National Science Foundation and the

University of Richmond Undergraduate Research Committee.

Sequences with the shared autocorrelation property, Corneliu Bodea, Calina Copos, Matt Der, David Oneal, Summer 2008.

Sponsored by the National Science Foundation.

Sequences with the shared autocorrelation property, Calina Copos, Matt Der, David Oneal, and Lauren Vanson,

Summer 2007. Sponsored by the National Science Foundation.

Reversible difference sets in 2-groups, Ryan Daut, Summer 2005. Sponsored by the National Security Agency.

A search for new partial difference sets, Peter Magliaro and Adam Weaver, Summer 2003.  Sponsored by the
National Security Agency.

Partial difference sets in new groups, Tiffany Broadbent and Ed Kenney, Summer 2002.  Sponsored by the University
of Richmond Undergraduate Research Committee, Collaborative Research Grant.

Difference sets in 2-groups and their associated codes,Mohammed Abouzaid and Jamie Bigelow, Summer, 2000.

Construction of New Asymptotic Classes of Binary Sequences Based on Existing Asymptotic Classes, Anthony
Kirilusha and Ganesh Narayanaswamy, summer 1999.  Sponsored by Hewlett-Packard.

Intersections of Golay codes with higher order Kerdock codes, Mohammed Abouzaid and Nick Gurski, summer

An examination of codewords with optimal merit factor, Mike Cammarano and Anthony Kirilusha, summer, 1998.

Octary codewords with peak power 3.2^m, Katie Nieswand and Kara Wagner, summer, 1998. Sponsored by
Hewlett-Packard.

Using the Quantum Computer to break and Elliptic Curve Cryptosystem, Jodie Eicher and Yaw Opoku,
summer, 1997. This won the Student Research Symposium Natural Science Award at the University of Richmond
in spring, 1998. Sponsored by Hewlett-Packard.

Power control in Golay cosets, Mike Cammarano and Meredith Walker, summer, 1997.  Sponsored by
Hewlett-Packard.

Coding theory over Galois Rings, Sarah Spence and Brian McKeever, Summer, 1995.  This won a poster
presentation at the annual Joint Math meetings of the American Mathematical Society and the Mathematics
Association of America in January, 1996.

PH.D. DISSERTATION DIRECTED:
Constructing partial difference sets using Galois Rings, John Polhill, University of Virginia, 1999.

GRANTS:

National Science Foundation, LURE, 2008-2011, $100,000 National Science Foundation, LURE, 2007-2011,$1,500,000.

National Security Agency Grant, salary, travel expenses, and support for undergraduate research, January
2003-December 2005.

University of Richmond Undergraduate Research Commmittee Collaborative Grant, salary and travel for me
and two students, summer 2002.

Hewlett-Packard Grant for Leave of Absence, academic year 2000-2001, paying salary, moving expenses, cost
of living expenses, and benefits.

Hewlett-Packard Grant for undergraduate summer research institute, May 1997-August 2000, to fund 4 students
full time working on applied problems.

Hewlett-Packard sabbatical Grant, August 1995-August 1996, funded move to England, half salary, other

National Security Agency Young Investigator Grant, June 1995-June 1997, summer salary and travel.

University of Richmond Summer Research Grant, Summer 1994, salary.

National Security Agency Young Investigator Grant, June 1992-June 1994, summer salary and travel.

Hewlett-Packard equipment grant (50 graphing calculators and supporting equipment), summer 1993.

University of Richmond Summer Research Grant, Summer 1989, salary.

CONSULTING:

Testifying Expert for Apple in Patent dispute, October 2011-June 2012.  Deposed on April 10, 2012, testified

at trial on June 12, 2012. Wrote Markman report (claims constructions), Invalidity report, Rebuttal non-

infringement report.

Consultant for Hewlett-Packard, August 1996-August 2000. Worked on patent preparation, standards

body submissions, basic research.

GRANTED PATENTS:

K.K. Smith, J. Jedwab, J.A. Davis, D. Banks and S.R. Wyatt, System for error correction coding and decoding,

U.S. Patent No. 7418644, 26 Aug 2008.

D. Banks, J. Davis, and J. Jedwab, Identifying uncorrectable codewords in a Reed-Solomon decoder for

errors and erasures, US Patent No. 7278086, 2 October 2007.

J. Davis, K. Eldredge, J. Jedwab, G. Seroussi, and K. Smith, MRAM with controller, US Patent No. 7266732,

4 September 2007.

S.M. Brandenberger, T. Munden, J. Jedwab, J. Davis, and D. Banks, System and method for

configuring a solid-state storage device with error correction coding, U.S. Patent No. 7,210,077, 24 Apr 2007.

J. Jedwab, J.A. Davis and G. Seroussi, Method for error correction decoding in a magnetoresistive

Solid-state storage device, U.S. Patent No. 7,149,949, 12 Dec 2006.

J.A. Davis, J. Jedwab, S. Morley, K.G. Paterson, F.A. Perner, K.K. Smith and S.R. Wyatt, Manufacturing

Test for a fault tolerant magnetoresistive solid-state storage device, U.S. Patent No. 7,149,948, 12 Dec 2006.

J. Jedwab, J.A. Davis, K.G. Paterson and G. Seroussi, Manufacturing test for a fault tolerant

magnetoresistive solid-state storage device, U.S. Patent No. 7107508, 12 Sep 2006.

J.A. Davis, J. Jedwab, S. Morley, and K.G. Paterson, Magnetoresistive solid-state storage device and

Data storage methods therewith, U.S. Patent No. 7,107,507, 12 Sep 2006.

Error correction coding and decoding in a solid-state storage device, (with J. Jedwab);

U.S. Patent No. 7,036,068, 25 April 2006.

Method for error correction decoding in an MRAM device (historical erasures), (with J. Jedwab,

K.G. Paterson, and G. Seroussi);  U.S. Patent No. 6,990,622, 24 Jan 2006.

Data storage method for use in a magnetoresistive solid-state storage device, (with J. Jedwab,

K.G. Paterson, G. Seroussi and K. Smith); U.S. Patent No. 6,981,196, 27 Dec 2005.

Allocation of sparing resources in a magnetoresistive solid-state storage device, (with Jedwab);

U.S. Patent No. 6,973,604, 6 Dec 2005.

Methods and apparatus for encoding and decoding data, European patent application No. 97 3
10252.8-2209 (with Jedwab); US patent 6,373,859, granted April 16, 2002.

Method and apparatus for decoding data, (with Jedwab and Paterson); US patent 6,487,258, granted
November 26, 2002.

System and Method for Transmitting Data, US patent 6,119, 263, granted September 12, 2000.

PENDING PATENTS:
Method and apparatus for decoding COFDM-data, European patent application No. 98 3 10269.0 (with
Jedwab and Paterson).

Complementary CRC polynomials, European patent application No. 97 3 02 946.5 (with Mowbray).

Error correction coding and decoding in a solid-state storage device (with Jedwab,
McIntyre,Paterson,Perner,Seroussi, and Smith), US Patent application
No. 2003/0023923.

Fault tolerant magnetoresistive solid-state storage device (with Eldredge,Jedwab,
McCarthy,Morley,Paterson,Perner,Smith, and Wyatt), US Patent application
No. 2003/0023922.

HONORS AND AWARDS:
University of Richmond Outstanding Mentor Award, 2004.

University of Richmond Distinguished Educator, 2000.

Roger Francis and Mary Saunders Richardson Chair of Mathematics, 1998-present.

President's Fellowship for graduate study, University of Virginia, l983-86.

Phi Beta Kappa, l983.

Francis Shunks Downs Award for leadership, awarded by the President of Lafayette College, 1983.

PUBLICATIONS:
Linking systems in nonelementary abelian groups, with J. Polhill and W. Martin, submitted.

Antiderivatives of Boolean functions, with G. McGrew, D. Steele, and K. Marsten, submitted.

New product constructions of partial difference sets, with J. Polhill and K. Smith, Designs, Codes,

and Cryptography, Online First, 11 February 2012.

Shared Autocorrelation property of sequences, with C. Bodea, C. Copos, M. Der, and D. O'Neal,

IEEE Transactions on Information Theory, Vol. 57 issue 6, 3805-3809, June 2011.

On the nonexistence of a projective (75,4,12,5) set in PG(3,7), with A. Chan and J. Jedwab, Journal

Of Geometry, vol. 97 pp. 29-44, 2010.

Novel Classes of Minimal Delay and Low PAPR Rate 1/2 Complex Orthogonal Designs, with S. Adams, N. Karst, M. K. Murugan,

B. Lee, IEEE Trans. on Inf. Th., Vol. 57 issue 4, 2254-2262, April 2011.

Difference set constructions of DRADs and association schemes, with J. Polhill, J. Comb. Th. (A),

Vol. 117 Issue 5, 598-605, July 2010.

G-perfect Nonlinear Functions, with L. Poinsot, Designs, Codes and Cryptography 46:1 January 2008

The design of the IEEE 802.12 coding scheme, with S. Crouch and J. Jedwab, IEEE Transactions on

Communications, October 2007

Proof of the Barker array conjecture, with J. Jedwab and K. Smith, Proceedings of the AMS,

Vol. 135, 2011-2018, 2007.

New amorphic association schemes, with Q. Xiang, Finite Fields and their Applications, Vol. 12,

595-612, 2006.

Negative Latin square type partial difference sets in nonelementary abelian 2-groups, with Q. Xiang,
J. London Math. Soc., Vol. 70 issue 1, 125-141, 2004.

Exponential numbers of inequivalent difference sets in Z_{2^{s+1}}^2, with D. Smeltzer, Journal of
Combinatorial Designs, Vol. 11 number 4, 249-259, 2003.

A Family of partial difference sets with Denniston parameters in nonelementary abelian 2-groups, with
Q.Xiang, The European Journal of Combinatorics, Vol. 00, 1-8, 2000.

Constructions of low rank relative difference sets in 2-groups using Galois rings, with Q.Xiang, Finite Fields
and their Applications 6, 130-145, 2000.

A unified approach to difference sets with gcd(v,n)>1, with J. Jedwab, in T.Helleseth et al.,eds., NATO
Science Series C, Difference Sets, Sequences and Their Correlation Properties, Vol. 542, Kluwer Academic
Publishers, editor A. Pott and others, 85-112, Dordrecht.

Codes, correlations and power control in OFDM, with J.Jedwab and K.Paterson, in T.Helleseth et al., eds.,
NATO Science Series C, Difference Sets, Sequences and Their Correlation Properties, Vol. 542, Kluwer
Academic Publishers, editor A. Pott and others, 113-132, Dordrecht.

A new family of relative difference sets in 2-groups, with J. Jedwab, Designs, Codes, and Cryptography
Memorial Volume for Ed Assmus, Vol. 17, 305-312, 1999.

Peak-to-mean power control in OFDM, Golay complementary sequences and Reed-Muller codes, with
J.Jedwab, IEEE Transactions on Information Theory, Vol. 45, 2397-2417, 1999.

Some recent developments in difference sets, with J.Jedwab, in K. Quinn, B. Webb, F. Holroyd and
C. Rowley, eds., Pitman Research Notes in Mathematics,Combinatorial Designs and their Applications,

A unifying construction for difference sets, with J.Jedwab, Journal of Combinatorial Theory Series (A),
Vol. 80 No.1, 13-78, Oct. 1997.

Hadamard difference sets in nonabelian 2-groups, with J.Iiams, Journal of Algebra, 199, 62-87, 1998.

Nested Hadamard difference sets, with J. Jedwab, Journal of Statistical Planning and Inference, vol. 62,
13-20, 1997.

Finding cyclic redundancy check polynomials for multilevel systems, with M.Mowbray and S.Crouch,
IEEE Transactions on Communications, October, 1998, Vol. 46, Number 10, 1250-1253.

Peak-to-Mean power control and error correction for OFDM transmission using Golay sequences and
Reed-Muller codes, with J.Jedwab, Electronics Letters, Vol. 33 No.4, 267-268, 13 February 1997.

New families of semi-regular relative difference sets, with J.Jedwab and M.Mowbray, Designs,
Codes, and Cryptography 13, 131-146, 1998.

New semi-regular divisible difference sets, Discrete Mathematics, 188, 99-109, 1998.

Construction of relative difference sets in 2-groups using the simplex code, with S.Sehgal, Designs,
Codes, and Cryptography, 11, 1-11, 1997.

Recursive construction for families of difference sets, with J. Jedwab, Bulletin of the ICA, vol. 13,
p. 128, 1995, Research announcement.

Partial difference sets in p-groups, Archiv Mathematik, 63, 103-110, 1994.

A Survey of Hadamard difference sets, with J. Jedwab, In K.T. Arasu et.al., editors, Groups, Difference
Sets, and the Monster, 145-156, de Gruyter, Berlin-New York, 1996.

Exponent bounds for a family of abelian difference sets, with K.T.Arasu, J.Jedwab, S.L. Ma, and R.
McFarland, In K.T. Arasu et.al., editors, Groups, Difference Sets, and the Monster, 145-156, de Gruyter,
Berlin-New York, 1996.

A nonexistence result for abelian Menon difference sets using perfect binary arrays, with K.T.Arasu
and J.Jedwab, Combinatorica, 15 (3), 311-317, 1995.

A construction of difference sets in high exponent 2-groups using representation theory, with K. Smith,
Journal of Algebraic Combinatorics, Vol. 3, 137-151, 1994.

A note on new semiregular divisible difference sets, with J. Jedwab, Designs, Codes, and Cryptography, 3,
379-381, 1993.

Almost difference sets and reversible divisible difference sets, Archiv Mathematik, Vol. 59, 595-602, 1992.

Reply to Comment on Nonexistence of certain perfect binary arrays'' and `Nonexistence of perfect binary
arrays,'' ', with J.Jedwab, Electronics Letters, vol. 29 p. 1002, 1993.

A summary of Menon difference sets, with J. Jedwab, Congressus Numerantium, vol. 93, 203-207, 1993.

Nonexistence of certain perfect binary arrays, with J.Jedwab, Electronics letters, 29 No.1, 99-100, Jan.1992.

New constructions on Menon difference sets, with K.T. Arasu, J. Jedwab, and S.K. Sehgal, Journal of
Combinatorial Theory Series A, Vol. 64 No.2, 329-336, Nov. 1993.

New constructions of divisible designs, Discrete Mathematics, Vol. 120, 261-268, 1993.

An exponent bound for relative difference sets in p-groups, Ars Combinatoria, 34, 318-320, 1992.

Construction of relative difference sets in p-groups, Discrete Mathematics, 103, 7-15, 1992.

A note on products of relative difference sets, Designs, Codes, and Cryptography, 1, 117-119, 1991.

A note on intersection numbers of difference sets, with K.T. Arasu, D.Jungnickel, and A.Pott, European
Journal of Combinatorics, 11, 95-98,1990.

Some nonexistence results on divisible difference sets, with K.T.Arasu, D.Jungnickel, and A.Pott,
Combinatorica, 11, 1-8, 1991.

A generalization of Kraemer's result on difference sets, Journal of Combinatorial Theory Series A, March,
1992, 187-192.

A result on Dillon's conjecture, Journal of Combinatorial Theory Series A, July 1991, 238-242.

A note on nonabelian (64,28,12) difference sets, Ars Combinatoria, 32, 311-314, 1991.

Difference sets in nonabelian 2-groups, Coding Theory and Design Theory, Part II, IMA, v.21, 65-69,
Springer-Verlag.

Difference sets in abelian 2-groups, Journal of Combinatorial Theory Series A,  July, 1991, 262-286.

SUBMISSIONS TO INTERNATIONAL NETWORKING STANDARDS:
Low complexity decoding for power controlled OFDM codes, with J. Jedwab and K.G. Paterson,
ETSI BRAN Working Group 3 (Hiperlan Type 2) Temporary Document 3hpl081a, March-April 1998.

Options for variable rate coding in OFDM using binary, quaternary and octary modulation, with J. Jedwab,
A. Jones, K. Paterson, and T. Wilkinson, ETSI BRAN Working Group 3 (Hiperlan Type 2) Temporary
Document 50, Sept 1997.

EXPOSITORY ARTICLES:
The most exciting thing ever in mathematics, New Book of Popular Science, Grolier, 1994.

How do we know that anything is true?, New Book of Popular Science, Grolier, 1993.

From schoolgirls to CDs to Outer Space, New Book of Popular Science, Grolier, 1992.

PRESENTATIONS:
What do those engineers do? Penn State Harrisburg, April 2012.

Difference sets, Virginia Commonwealth University, November 2011.

Difference sets and Association Schemes, AMS sectional in Lincoln Nebraska, October 2011.

Difference sets and Association Schemes, Finite Geometries in IRSEE, Germany, June 2011.

McFarland difference sets and Association schemes, Vancouver, Canada, June 2010.

Difference sets and DRADs, Finite Fields and their Applications, Dublin, Ireland, June 2009.

Linear algebra is the answer to everything: an industrial research mathematics problem, Bloomsburg University colloquim, April 2005.

Relative difference sets and cohomology, a preliminary study, University of Delaware discrete mathematics seminar, October 2004.

Bluffhead and other games, Cool Math seminar, University of Richmond, September 2004.

The mathematics of 100 base vg, Central Michigan University Colloquium, February 2004.

The mathematics of 100 base vg, Simon Fraser University Colloquium, January 2004.

The mathematics of 100 base vg, National meeting of the American Mathematical Society,
Phoenix, January 2004.

Negative Latin Square type partial difference sets in non-elementary abelian groups,
The British Combinatorial Conference, July, 2003.

Finite Geometry meets Galois Rings: the search for Denniston Partial Difference Sets,
University of Richmond Colloquium, March, 2002.

Inequivalent difference sets, University of Delaware Combinatorics Seminar, October, 2001.

Finite Geometry meets Galois Rings: Construction of Denniston Partial Difference
Sets, The National University of Ireland, Maynooth, October, 2000.

The XTR Cryptosystem, University of Bristol/Hewlett-Packard
Cryptography Seminar, February, 2001.

Denniston partial difference sets, The National University of Singapore, June, 2000.

Denniston partial difference sets, The Ohio State-Denison conference, May, 2000.

The game of SETS and coding theory, Greater Richmond Council of Teachers of Mathematics, March, 2000.

Relative difference sets and Galois Rings, conference in Augsburg, Germany, August, 1999.

Relative difference sets in groups whose order is not a prime power, seminar at the University of Delaware,
March, 1999.

Golay complementary sequences and Reed-Muller codes, conference in Bad Windsheim, Germany,
August 6, 1998.

Unifying construction for difference sets, Part II, conference in Bad Windsheim, Germany, August 5, 1998.

Unifying construction for difference sets, Part I, conference in Bad Windsheim, Germany, August 4, 1998.

Beauty and the mathematician, Lunchtime forum, University of Richmond, December, 1997.

Construction of relative difference sets in groups of non-prime power order, British Combinatorial
Conference, July, 1997.

The Kirkman schoolgirl problem to error correcting codes, Randolph-Macon College colloquium,
November, 1996.

The Kirkman schoolgirl problem to error correcting codes, University of Richmond colloquium,
September, 1996.

From the Kirkman schoolgirl problem to error correcting codes: different views of difference sets,
The University of Wales at Aberystwyth colloquium, May, 1996.

A unifying construction of difference sets, The Basic Research in Mathematical Sciences (BRIMS)
colloquium, Bristol, England, April, 1996.

A unifying construction of difference sets, Institut fur Mathematik der Universitat Augsburg, Augsburg,
Germany, March, 1996.

A recursive construction of Relative difference sets, Royal Holloway University, London, England,
February, 1996.

A recursive construction of Relative difference sets, Bose Memorial Conference, Ft. Collins CO, June 1995.

A new family of difference sets, National Security Agency, May 1995.

K-matrices revisited, Special Session on Codes and Designs, University of Richmond, Nov, 1994.

Partial difference sets in p-groups, The Ohio State University/Denison University conference, March 1994.

If at first you don't succeed... a search for difference sets, Virginia Commonwealth University
colloquium, November, 1993.

Partial results on partial difference sets, the British Combinatorial Conference, July, 1993.

Nonexistence results on difference sets, the conference on Difference Sets at Ohio State University, May,
1993 (one hour talk).

A survey of Menon difference sets-- the nonabelian case, Southeastern Combinatorics conference, Feb. 1993.

Difference sets and perfect binary arrays, William and Mary colloquium, Jan. 1993.

If at first you don't succeed... a search for difference sets, Central Michigan University colloquium, May, 1992.

If at first you don't succeed... a search for difference sets, talk to Ohio State combinatorics seminar, May, 1992.

New constructions of divisible designs, the conference at Denison University, May, 1992.

Almost difference sets and divisible difference sets with multiplier -1, special session on Designs and Codes,
Joint meeting of the MAA and AMS, Baltimore, January 1992.

Error Correcting Codes, Sigma Xi lecture, University of Richmond, December, 1990.

Relative Difference Sets in p-Groups, Oberwolfach, April, 1990.

Coding Theory, Hampden-Sydney colloquium, October, l988.

Character Theory Applied to Difference Sets, Design Theory Workshop, IMA, June, l988.

Difference Sets in Abelian 2-Groups, Joint National Meeting of the AMS-MAA, January, l988.

Difference Sets in Abelian 2-Groups, Wright State University colloquium, January, l988.

Difference Sets in Abelian 2-Groups, National Security Agency seminar, January, l987.

OTHER CONFERENCES AND COLLABORATIONS:
Codes and Designs, Oberwolfach, March, 1998.

Trip to Technion University, Haifa, Israel to collaborate with mathematicians, March, 1998.

CLASSES TAUGHT:
100 level: Introduction to Statistics, Statistics for the Social Sciences, Calculus with precalculus.

200 level: Discrete math, Calculus 1, Calculus 2, Multivariate Calculus, Linear Algebra.

300 level: Abstract Algebra 1, Abstract Algebra 2, Coding Theory, Cryptography.

SERVICE:
Chair, hiring committee, 2001-2002.

Chair, General Education Committee, 2001-2002.

Chair of Math and Computer Science department, 1997-2000, spring 2005.

Ethyl Committee, 1994-present.

Chair, hiring committee, 1994-95.

Curriculum committee, 1993-95.

Colloquium chair, 1991-94.