Thomas J. Laffey | Academic Influence

Thomas J. Laffey's AcademicInfluence.com Rankings

Thomas J. Laffey

Mathematics

#5134

World Rank

#7254

Historical Rank

Group Theory

#173

World Rank

#205

Historical Rank

Algebra

#263

World Rank

#379

Historical Rank

Number Theory

#331

World Rank

#412

Historical Rank

mathematics Degrees

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Mathematics

Thomas J. Laffey's Degrees

Masters Mathematics National University of Ireland
Bachelors Mathematics National University of Ireland

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Why Is Thomas J. Laffey Influential?

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According to Wikipedia, Thomas J. Laffey is an Irish mathematician known for his contributions to group theory and matrix theory. His entire career has been spent at University College Dublin , where he served two terms as head of the school of mathematics. While he formally retired in 2009, he remains active in research and publishing. The journal Linear Algebra and Its Applications had a special issue to mark his 65th birthday. He received the Hans Schneider Prize in 2013. In May 2019 at UCD, the International Conference on Linear Algebra and Matrix Theory held a celebration to honor Professor Laffey on his 75th birthday.

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Thomas J. Laffey's Published Works

Number of citations in a given year to any of this author's works

Total number of citations to an author for the works they published in a given year. This highlights publication of the most important work(s) by the author

Published Works

Real-Time Knowledge-Based Systems (1988) (331)
The Topographic Primal Sketch (1983) (305)
Checking an Expert Systems Knowledge Base for Consistency and Completeness (1985) (241)
Knowledge base verification (1987) (229)
Products of Matrices (1991) (88)
The real and the symmetric nonnegative inverse eigenvalue problems are different (1996) (79)
Topographic classification of digital image intensity surfaces using generalized splines and the discrete cosine transformation (1984) (69)
A characterization of trace zero nonnegative 5×5 matrices (1999) (62)
Nonnegative realization of spectra having negative real parts (2006) (56)
Nonnegative factorization of completely positive matrices (1983) (53)
Linear operators on matrices: The invariance of rank-k matrices (1988) (52)
Simultaneous triangularization of matrices—low rank cases and the nonderogatory case (1978) (50)
Reasoning About Fault Diagnosis with LES (1986) (46)
Real rank versus nonnegative rank (2009) (40)
The minimal dimension of maximal commutative subalgebras of full matrix algebras (1985) (35)
Simultaneous reduction of sets of matrices under similarity (1986) (33)
Extreme nonnegative matrices (1998) (33)
Construction of nonnegative symmetric matrices with given spectrum (2007) (32)
Two-generated commutative matrix subalgebras (1991) (29)
Algebras generated by two idempotents (1981) (28)
A refinement of an inequality of Johnson, Loewy and London on nonnegative matrices and some applications (1998) (28)
A resolution of Paz's conjecture in the presence of a nonderogatory matrix (2018) (28)
Linear transformations on that preserve the Ky Fan k-norm and a remarkable special case when (n k) = (4, 2) (1988) (25)
A lemma on finite p-groups and some consequences (1974) (25)
Pairs of alternating forms and products of two skew-symmetric matrices (1984) (24)
The Minimum Number of Generators of a Finite p‐Group (1973) (23)
Products of idempotent matrices (1983) (22)
Tensor conditions for the existence of a common solution to the Lyapunov equation (2007) (21)
A constructive version of the Boyle-Handelman theorem on the spectra of nonnegative matrices (2010) (20)
A counterexample to kippenhahn's conjecture on hermitian pencils (1983) (18)
Intelligent Real-Time Monitoring (1988) (18)
Perturbing non-real eigenvalues of nonnegative real matrices (2005) (16)
Automorphism orbits of finite groups (1986) (16)
Pairs Of Matrices With Quadratic Minimal Polynomials (1983) (16)
Centralizers of elementary Abelian subgroups in finite p-groups (1978) (13)
Nonnegatively realizable spectra with two positive eigenvalues (2010) (12)
Rule-Based Interpreting Of Aerial Photographs Using LES (1985) (12)
Integral similarity and commutators of integral matrices (1994) (12)
On Commutative Subrings of Infinite Rings (1972) (12)
The number of solutions ofx3=1 in a 3-group (1976) (12)
On the higher relation modules of a finite group (1979) (11)
Checking a Knowledge-Based System for Consistency and Completeness (1987) (11)
Common Lyapunov solutions for two matrices whose difference has rank one (2009) (11)
Factorizations of integer matrices as products of idempotents and nilpotents (1989) (11)
Simultaneous quasidiagonalization of complex matrices (1977) (10)
LES: A General Expert System And Its Applications (1984) (10)
The Diagonalizable Nonnegative Inverse Eigenvalue Problem (2017) (10)
On the decomposition of the exterior square of an indecomposable module of a cyclic p-group (2006) (10)
Power series with positive coefficients arising from the characteristic polynomials of positive matrices (2012) (10)
Common solution to the Lyapunov equation for 2 × 2 complex matrices☆ (2007) (10)
On a classic example in the nonnegative inverse eigenvalue problem (2008) (10)
The number of solutions of xp = 1 in a finite group (1976) (9)
On a conjecture of Wilf (2006) (9)
Knowledge-Based Diagnosis of Electronic Instrumentation (1985) (8)
On the structure of algebraic algebras. (1976) (8)
A NOTE ON EMBEDDING FINITE SEMIGROUPS IN FINITE SEMIBANDS (1983) (8)
The effect of assuming the identity as a generator on the length of the matrix algebra (2015) (7)
On a conjecture of Deveci and Karaduman (2015) (7)
Real-time analysis of telemetry data (1987) (7)
Making the message clear (1997) (7)
A structure theorem for some matrix algebras (1992) (7)
A basis theorem for matrix algebras (1980) (6)
Infinite Rings with All Proper Subrings Finite (1974) (6)
Commutative Subalgebras of Infinite Dimensional Algebras (1973) (6)
Lectures on Integer Matrices (2002) (6)
A normality criterion for an algebra of matrices (1979) (6)
Simultaneous triangularization of a pair of matrices (1977) (6)
SEMITRANSITIVE SUBSPACES OF MATRICES (2006) (6)
The Topographic Primal Sketch and Its Application to Passive Navigation (1983) (6)
FORMAL POWER SERIES AND THE SPECTRA OF NONNEGATIVE REAL MATRICES (2013) (5)
LES: (Lockheed Expert System): A Model-Based Expert System for Electronic Maintenance, (1984) (5)
Sufficient Conditions on Commutators for a Pair of Stable Matrices to Have a Common Solution to the Lyapunov Equation (2010) (5)
Invariant Subspaces for Semigroups of Algebraic Operators (1998) (5)
On the second eigenvalue of matrices associated with TCP (2006) (5)
Irredundant generating sets for matrix algebras (1983) (5)
Integer completely positive matrices of order two (2018) (5)
Conjugacy and factorization results on matrix groups (1994) (4)
Spectra of principal submatrices of nonnegative matrices (2008) (4)
Pure Shear – A Footnote (2008) (4)
Completely positive factorizations associated with Euclidean distance matrices corresponding to an arithmetic progression (2019) (4)
CLASS ACTION COMPLAINT FOR VIOLATIONS OF THE FEDERAL SECURITIES LAWS (2000) (4)
The Hughes problem for exponent nine (1980) (4)
Spectral classification of projections (1981) (4)
An inequality for the spectra of nonnegative matrices (2012) (4)
A criterion for generating full matrix algebras (1981) (3)
On Minimal Sylow Intersections (1976) (3)
A note on matrix subalgebras containing a full Jordan block (1981) (3)
Perturbations on constructible lists preserving realizability in the NIEP and questions of Monov (2014) (3)
SOME ASPECTS OF OLGA TAUSSKY'S WORK IN ALGEBRA (1998) (3)
Similarity classes and principal submatrices (2005) (3)
Simultaneous triangularization of a pair of matrices whose commutator has rank two (1980) (3)
An extension of a factorization theorem of wedderburn to matrix rings (1992) (3)
A Remark on Minimal Sylow Intersections (1972) (3)
A problem on cyclic subgroups of finite groups (1973) (3)
A note on subfields of matrix rings (1977) (3)
Commutative subrings of periodic rings. (1976) (3)
On the stability of convex sums of rank-1 perturbed matrices (2002) (2)
Nonnegative Matrices That Are Similar to Positive Matrices (2009) (2)
Factorization of polynomials using commuting matrices (1994) (2)
On the Radius in Cayley-Dickson Algebras (2015) (2)
Report on the Dublin matrix theory conference, March 1984: Products of skew-symmetric matrices (1985) (2)
The mathematical work of Walter Ledermann (1985) (2)
Subfields of matrix rings (1979) (2)
A sparsity result on nonnegative real matrices with given spectrum (1997) (2)
Linear preservers of matrices of rank-2 (2001) (2)
A multiprocessing architecture for real-time monitoring (1988) (1)
A characterisation of full matrix algebras (1984) (1)
Fault diagnosis: Engineers and troubleshooters combine forces to create a knowledge-based system for the aerospace industry (1986) (1)
The Karpelevič region revisited (2020) (1)
Finite Groups with a Unique Minimal Normal Subgroup (1972) (1)
PERTURBING NON-REAL EIGENVALUES OF NONNEGATIVE (2005) (1)
Report on the Dublin matrix theory conference, March 1984: Matrices over finite fields Graciano de Oliveira Departamento de Matemática Universidad de Coimbra Coimbra, Portugal (1985) (1)
Solubility theorems for finite groups (1973) (1)
Simultaneous reduction of matrices in the presence of a nonderogatory matrix (2013) (1)
Disjoint conjugates of cyclic subgroups of finite groups (1977) (1)
Elementary Problems: E3269-E3275 (1988) (0)
The integer cp-rank of 2 × 2 matrices (2019) (0)
Real-Time Knowledge-Based Monitoring Of Telemetry Data (1988) (0)
Ela a Refinement of an Inequality of Johnson, Loewy and London on Nonnegative Matrices and Some Applications (1998) (0)
Knowledge-based monitoring of the pointing control system on the Hubble space telescope (1987) (0)
Factorization of polynomials using nilpotent Jordan blocks (1992) (0)
EDITORIAL (2006) (0)
CHECK identifies inconsistencies in the knowledge base by looking for redundant rules , conflicting rules , subsumed rulesqnnecessary (2001) (0)
On a question of Hills concerning co-transposers (1986) (0)
Power series with positive coefficients arising from the characteristic polynomials of positive matrices (2015) (0)
The Karpelevi\v{c} Region Revisited (2020) (0)
The integer cp-rank of $2 \times 2$ matrices (2019) (0)
Diagonal realizability in the Nonnegative Inverse Eigenvalue Problem (2018) (0)
Lockheed Expert System - putting knowledge-based systems to work at Lockheed (1986) (0)
Limiting Values of the Variance and the Moments or Intersection of of the Dimension of a Sum Random Vector Subspaces (2002) (0)
P-soluble linear groups with Sylow p-intersections of small rank (1979) (0)
Measurement Of The 3D Radius Of Curvature Using The Facet Approach (1986) (0)
The Economic Impact of Dickinson College on Carlisle and Cumberland County, 2010. (2010) (0)
Convergence rates for second moments of networks of long-lived TCP flows (2006) (0)
Thanks to Referees (2011) (0)
Special Issue in honor of Jose Dias da Silva (2010) (0)
Real-time AI: myth or reality? (1991) (0)
The life and work of Fergus Gaines ( 1939 – 2001 ) (2002) (0)

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