David Horn (Hebrew: דוד הורן; born September 10, 1937, in Haifa, Mandatory Palestine, now Israel) is a Professor Emeritus of Physics in the School of Physics and Astronomy at Tel Aviv University in Israel. His fields of research encompass physics, neural computation, and bioinformatics. Associated with the Hebrew University and Technion, he completed his 1965 doctoral dissertation, titled "Some Aspects of the Structure of Weak Interactions", under the supervision of Yuval Ne'eman.

During his career at Tel Aviv University, he has served as Vice-Rector, Chairman of the School of Physics and Astronomy, and Dean of the Faculty of Exact Sciences.^[1] He is a fellow of the American Physical Society, recognized for his contributions to theoretical particle physics, including seminal work on finite energy sum rules, research into the phenomenology of hadronic processes, and the investigation of Hamiltonian lattice theories.^[2]

David Horn was born, raised, and educated in Haifa. He graduated from the Hebrew Reali School in Haifa in 1955. In 1957, he began his academic studies in physics at the Technion in Haifa, receiving his B.Sc. with highest honors (summa cum laude) in 1961 and his M.Sc. in 1962. He continued his doctoral studies at the Hebrew University of Jerusalem, receiving his Ph.D. in 1965 with a dissertation titled "Some Aspects of the Structure of Weak Interactions," supervised by Prof. Yuval Ne'eman.^[3]

Horn joined Tel Aviv University in 1962 as a research assistant. In 1965, he was appointed a lecturer, becoming a senior lecturer two years later, an associate professor in 1968, and a full professor in 1972. Two years later, he was appointed to the Edouard and Francoise Jaupart Chair of Theoretical Physics of Fields and Particles, holding it until 2007. Over the years, Horn supervised 43 graduate students, including Prof. Marek Karliner, and published more than 240 research papers. He retired as professor emeritus in 2005 and continues his research.

Horn served as a visiting researcher and professor at various academic institutions and research institutes, including as a postdoctoral fellow at the Argonne National Laboratory in Illinois, a research fellow and three-time visiting researcher at the California Institute of Technology in Pasadena, a visiting researcher at CERN in Geneva, a member of the Institute for Advanced Study in Princeton, New Jersey, and a visiting professor at Cornell University in New York, the SLAC laboratory at Stanford University, and Kyoto University in Japan. At Tel Aviv University, he held various managerial roles, serving as Vice Rector from 1980 to 1983 (a position he left in favor of research at SLAC), head of the Department of High Energy Physics from 1984 to 1986, head of the School of Physics and Astronomy from 1986 to 1989, Dean of the Raymond and Beverly Sackler Faculty of Exact Sciences from 1990 to 1995, and the first director of the Adams Super-Center for Brain Research from 1993 to 2000. In professional roles in Israel and internationally, Horn served as chairman of the High Energy Physics Committee from 1983 to 2003, acting in this role as an Israeli observer at CERN from 1991 to 2003, and was a member of the Council for Higher Education (1987–1991), a member of the Executive Committee of the European Physical Society (1989–1992), and Israel's representative in the European Strategy Forum on Research Infrastructures (2005–2017). During the years 2012–2016, he served as head of the Planning and Budgeting Committee's Research Infrastructures Committee, submitting on its behalf roadmaps for scientific research infrastructures in Israel in 2013 and 2016.

Horn joined the newly founded Tel Aviv University as an assistant in 1962, becoming a lecturer in 1965, a senior lecturer in 1967, and an associate professor in 1968. He was promoted to full professor of Physics in 1972, and in 1974 became the incumbent of the Edouard and Francoise Jaupart Chair of Theoretical Physics of Particles and Fields, a position he held until 2007. Over his career, Horn has supervised 43 graduate students at TAU, authored over 240 scientific publications, retired as a professor emeritus in 2005, and continues to be an active researcher.^[3,4] He also spent a significant part of his career holding visiting academic positions at other universities and research institutes, including serving as a Postdoctoral Fellow at Argonne National Lab, ILL, a Research Fellow and three-time Visiting Associate at the California Institute of Technology, Pasadena, CA, a Visitor at CERN in Geneva, a Visiting Professor at Cornell University, NY, a Member of the Institute for Advanced Study, Princeton, NJ, a Visiting Professor at SLAC in Stanford University, CA, and a Visiting Professor at Kyoto University, Japan.^[5]

Beginning in 1980, Horn held official administrative positions at Tel Aviv University, starting with tenure as Vice-Rector (1980-1983), a position he left for research at SLAC.^[6] After returning, he was nominated Chairman of the Department of High Energy Physics (1984-1986), followed by tenures as Chairman of the School of Physics and Astronomy (1986-9), Dean of the Raymond and Beverly Sackler Faculty of Exact Sciences (1990-1995), and first Director of the Adams Super Center for Brain Studies (1993-2000).^[8,9]

Horn has also held national and international professional positions, serving as Chairman of the Israel Commission for High Energy Physics (1983-2003) and, in this capacity, as an Israeli observer of the council of CERN (1991-2003).^[10] He served as a member of the Israel Council for Higher Education (1987-1991), a member of the Executive Committee of the European Physical Society (1989-1992), and a member of the European Strategy Forum on Research Infrastructures (2005-2017). Additionally, he chaired the Israeli Committee of Research Infrastructures (2012-2016), issuing roadmaps for scientific RI in 2013 and 2016.^[3,13]

Horn's research focused on the theory and phenomenology of high-energy physics until 1990, after which he shifted his interests to neural computation and machine learning, and began publishing in bioinformatics in 2005.^[11] Together with Richard Dolen and Christoph Schmid, he discovered the Finite Energy Sum Rules in 1967. This theory, which was a realization of the bootstrap approach to hadronic structure that bridged two ways of understanding the strong force acting between hadrons, became known as the Dolen-Horn-Schmid Duality.^[12,13] In 1971, together with Richard Silver, he investigated and developed a model of coherent production of pions in high-energy hadron collisions. In 1978, together with Jeffrey Mandula, he undertook the investigation of mesons with constituent gluons, exploring meson structures based on quarks and a gluon.^[15] Moving to lattice gauge theories in 1979, he discovered, together with Shimon Yankielowicz and Marvin Weinstein, a non-confining phase in Z(N) theories for large N.^[18,16,14] In 1981, he demonstrated the existence of finite matrix models with link gauge fields—lattice models with finite matrices at the vertices and continuous gauge fields connecting them—which are nowadays known as quantum link models.^[18,16,14] In 1984, Horn and Weinstein developed and published the t-expansion methodology of Hamiltonian lattice theories.^[19,17]

Horn's contributions to neural modeling and computation include a novel mechanism for memory maintenance via neuronal regulation developed in 1998 with Nir Levy and Eytan Ruppin.^[20] In 2005, joint work with Zach Solan, Eytan Ruppin, and Shimon Edelman on unsupervised natural language learning introduced novel algorithms for motif extraction and grammar induction from text. Horn also contributed to clustering algorithms, an important topic in machine learning, by developing Support Vector Clustering (SVC) in 2001 together with Asa Ben-Hur, Hava Siegelmann, and Vladimir Vapnik. This was followed shortly thereafter by joint work with Assaf Gottlieb developing Quantum Clustering (QC).^[21]

Horn's research in bioinformatics includes motif descriptions and characterization of protein function and structure, as well as motif studies of genomic structures. Together with Erez Persi, he studied the compositional order of proteomes and ordered structures in protein sequences, as well as genomic repeat instability and long repetitive DNA sequences as markers of organism evolution and cancer development (a joint work with Persi and others).^[25,22,23]

In particle and theoretical physics, David Horn co-authored with R. Dolen and C. Schmid the articles "Prediction of Regge-parameters of rho poles from low-energy pi-N scattering data" in Physical Review Letters (1967) and "Finite-Energy Sum Rules and Their Application to pi-N Charge Exchange" in Physical Review (1968). With R. Silver, he published "Coherent production of pions" in Annals of Physics (1971). Together with T. Banks and H. Neuberger, he authored "Bosonization of the SU(N) Thirring Models" in Nuclear Physics B (1976). Horn and J. Mandula published "Model of Mesons with Constituent Gluons" in Physical Review D (1978). Alongside M. Weinstein and S. Yankielowicz, he co-authored "Hamiltonian Approach to Z(N) Lattice Gauge Theories" in Physical Review D (1979). In 1981, he published "Finite Matrix Models with Continuous Local Gauge Invariance" in Physics Letters B. With T. Banks and Y. Dothan, he published "Geometric Fermions" in Physics Letters B (1982). In 1984, Horn and M. Weinstein authored "The t expansion: A nonperturbative analytic tool for Hamiltonian systems" in Physical Review D.

In neural networks and machine learning, Horn co-authored "Optimal Ensemble Averaging of Neural Networks" with Ury Naftaly and Nathan Intrator in Network: Computation in Neural Systems (1997). With Nir Levy and Eytan Ruppin, he published "Memory Maintenance via Neuronal Regulation" in Neural Computation (1998). In 2001, Asa Ben-Hur, David Horn, Hava Siegelmann, and Vladimir Vapnik published "Support Vector Clustering" in the Journal of Machine Learning Research. Horn and Assaf Gottlieb published "Algorithm for data clustering in pattern recognition problems based on quantum mechanics" in Physical Review Letters (2002). With Zach Solan, Eytan Ruppin, and Shimon Edelman, he authored "Unsupervised learning of natural languages" in the Proceedings of the National Academy of Sciences (2005).

In computational biology and genomics, Horn co-authored "Functional representation of enzymes by specific peptides" with Vered Kunik, Yasmine Meroz, Zach Solan, Ben Sandbank, Uri Weingart, and Eytan Ruppin in PLOS Computational Biology (2007). Benny Chor, David Horn, Yaron Levy, Nick Goldman, and Tim Massingham published "Genomic DNA k-mer spectra: models and modalities" in Genome Biology (2009). With Erez Persi, Horn published "Systematic Analysis of Compositional Order of Proteins Reveals New Characteristics of Biological Functions and a Universal Correlate of Macroevolution" in PLoS Computational Biology (2013). In 2013, Horn authored "Taxa counting using Specific Peptides of Aminoacyl tRNA Synthetases" in the Encyclopedia of Metagenomics published by Springer. Sagi Shporer, Benny Chor, Saharon Rosset, and Horn published "Inversion symmetry of DNA k-mer counts: validity and deviations" in BMC Genomics (2016). In 2019, Horn co-authored "Proteomic and Genomic Signatures of Repeat Instability in Cancer and Adjacent Normal Tissues" in PNAS alongside Erez Persi, Davide Prandi, Yuri I. Wolf, Yair Pozniak, Christopher Barbieri, Paola Gasperini, Himisha Beltran, Bishoy M. Faltas, Mark A. Rubin, Tamar Geiger, Eugene V. Koonin, and Francesca Demichelis.

His patents include "Method and Apparatus for Quantum Clustering" (USA Patent No. 7,653,646 B2). He also holds USA Patent No. 8874412 and USA Patent No. 9,646,074 for "Method for discovering relationships in data by dynamic quantum clustering".

Horn was married to Nira (née Fuss) from 1963 until her death in 2019. He is a father of three, Yuval, Tamar, and Oded, and grandfather of nine. He lives in Tel Aviv, Israel.

External resources include David Horn's profile at Tel Aviv University. Additionally, a YouTube recording is available for "Challenges of Science and Technology in the 21st Century," an interdisciplinary TAU symposium held in honor of David Horn on his 80th birthday.