Langis Gagnon, PhD
(Member: ACM, IEEE, SPIE)

R&D and Scientific Director
CRIM
(Centre de Recherche Informatique de Montréal)
langisDOTgagnonATcrimDOTca
I received a Ph.D. in Mathematical-Physics from Université de Montréal in 1988. My research gradually moved from PDE's solution based on group theory, to nonlinear optics, signal/image processing and then computer vision. I have extensive R&D, managing and scientific development experience, acquired in university, research center and industrial settings.

Current Positions

Past Positions

Main Publications (Journals and Proceedings)

Video Surveillance

  1. M. Lalonde, M. Derenne, L. Gagnon, D. Gorodnichy The Current State and TRL Assessment of Unattended and Left-Behind Object Detection Technology, Agence des Services frontaliers du Canada, Border Technology Division, Division Report 2014-13, 2014
  2. T. Landry, L. Gagnon, D. Laurendeau, A GIS-Centric Optical Tracking System and Lap Simulator for Short Track Speed Skating, 10th Conference on Computer and Robot Vision, Regina, 2013
  3. S. Foucher, M. Lalonde, L. Gagnon, A system for airport surveillance: detection of people running, abandoned objects and pointing gestures, SPIE Defense & Security Symposium: Visual Information Processing 2011
  4. M. Lalonde, S. Foucher, L. Gagnon, CRIM Notebook Paper – TRECVID 2010 – Surveillance Event Detection, NIST-TRECVID Evaluation Workshop 2010
  5. M. Lalonde, S. Foucher, L. Gagnon, Unconstrained License Plate Detection Using the Hausdorff Distance, Visual Information Processing, SPIE Defense and Security Symposium: Visual Information Processing 2010
  6. S. Foucher, M. Lalonde, L. Gagnon, Automatic Scene Modeling for Improving Object Classification, SPIE Defense and Security Symposium: Visual Information Processing 2010
  7. M. Lalonde, D. Byrns, L. Gagnon, E. Pronovost, M. Derenne, A. Janelle, A system to automatically track humans and vehicles with a PTZ camera, SPIE Defense & Security: Visual Information Processing XVI (SPIE #6575), Orlando, 2007
  8. A. Branzan Albu, D. Laurendeau, S. Comtois, D. Ouellet, P. Hébert, A. Zaccarin, M. Parizeau, R. Bergevin, X. Maldague, R. Drouin, S. Drouin, N. Martel-Brisson, F. Jean, H. Torresan, L. Gagnon, F. Laliberté, MONNET: Monitoring Pedestrians with a Network of Loosely-Coupled Cameras, ICPR, 2006
  9. L. Gagnon, F. Laliberté, S. Foucher, D. Laurendeau, A. Branzan Albu, A System for Tracking and Recognising Pedestrian Faces using a Network of Loosely Coupled Cameras, SPIE Defense & Security: Visual Information Processing XV (SPIE #6246), Orlando, 2006

Video Indexing

  1. V. Gupta, P. Darvish Zadeh Varcheie, L. Gagnon, G. Boulianne, Content-Based Video Copy Detection Using Nearest-Neighbor Mapping, Int. Conf. on Information Sciences, Signal Processing and their Applications 2012
  2. M. Héritier, V. Gupta, L. Gagnon, G. Boulianne, S. Foucher, P. Cardinal, CRIM's Content-Based Copy Detection System for TRECVID, TREC Video Retrieval Evaluation (TRECVID 2009)
  3. M. Héritier, S. Foucher, L. Gagnon, Video Copy Detection Using Latent Aspect Modeling Over SIFT Matches, TREC Video Retrieval Evaluation (TRECVID 2008)
  4. M. Héritier, L. Gagnon, S. Foucher, Places Clustering of Full-Length Film Key-frames using Latent Aspects Modeling over SIFT Matches, IEEE Trans. on Circuits and Systems for Video Technology, Vol. 19, No. 6, 2009
  5. K. Ryan, A. Amer, L. Gagnon, Spatio-Temporal Region Enhancement and Merging for Unsupervised Object Segmentation, EURASIP Journal in Image and Video Processing, 2009, 13 pages, doi:10.1155/2009/797052
  6. L. Gagnon, S. Foucher, Segmentation of non-natural objects in landscape images using ridgelet transform, Journal of Electronic Imaging, Vol. 18, No. 2, 2009
  7. M. Héritier, S. Foucher, L. Gagnon, Key-Places Detection and Clustering in Movie Using Latent Aspects, ICIP, San Antonio, 2007
  8. S. Foucher, L. Gagnon, Automatic Detection and Clustering of Actor Faces based on Spectral Clustering Techniques, 4th Conference on Computer and Robot Vision, Montréal, 2007
  9. M. Lalonde, L. Gagnon, Détection de texte dans des vidéos documentaires avec une cascade de classifieurs, CIFED, Fribourg, 2006
  10. K. Ryan, A. Amer, L. Gagnon, Video Object Segmentation Based on Object Enhancement and Region Merging, ICME, Toronto, 2006
  11. M. Lalonde, L. Gagnon, Key-text spotting in documentary videos using Adaboost, IS&T/SPIE Symposium on Electronic Imaging: Applicatons of Neural Networks and Machine Learning in Image Processing X (SPIE #6064B), San Jose, 2006
  12. L. Gagnon, R&D status of ERIC-7 and MADIS: two systems for MPEG-7 indexing/search of audio-visual content, SPIE Photonic East: Multimedia Systems and Applications VIII (SPIE #6015), Boston, 2005
  13. V. Gouaillier, L. Gagnon, S. Paquette, P. Poullaouec-Gonidec, Use of the MPEG-7 Standard as Metadata Framework for a Location Scouting System - An Evaluation Study, Dublin Core Conference, Madrid, 2005
  14. S. Foucher, L. Gagnon, Face Recognition in Video Using Dempster-Shafer Theory, ICASSP, Montréal, 2004
  15. L. Gagnon, S. Foucher, V. Gouaillier, ERIC7: A Generic Environment for Content-Based Image Retrieval within the MPEG-7 Standard, Winter International Symposium on Information and Communication Technologies, Cancun, 2004
  16. S. Foucher, V. Gouailllier, L. Gagnon, Global Semantic Classification of Scenes using Ridgelet Transform, IS&T/SPIE Symposium on Electronic Imaging: SPIE Human Vision (SPIE #5292), San Jose, 2004
  17. L. Gagnon, S. Foucher, V. Gouaillier, C. Brun, J. Brousseau, G. Boulianne, F. Osterrath, C. Chapdelaine, J. Dutrisac, F. St-Onge, B. Champagne, X. Lu, MPEG-7 Audio-Visual Indexing Test-Bed for Video Retrieval, IS&T/SPIE Symposium on Electronic Imaging: SPIE Internet Imaging V, San Jose, 2004

e-Accessibility

  1. M. Dahmane, L. Gagnon, Local Phase-Context for Face Recognition under Varying Conditions, 6th International conference on Intelligent Human Computer Interaction (IHCI), Paris, 2014
  2. L. Gagnon, C. Chapdelaine, D. Byrns, S. Foucher, M. Héritier, V. Gupta, Computer-Vision-Assisted System for Videodescription Scripting, Computer Vision Application for Visually-Impaired, a satellite workshop of Computer Vision and Pattern Recognition (CVPR) 2010
  3. C. Chapdelaine, L. Gagnon, Accessible Videodescription On-Demand, 11th International ACM SIGACCESS Conference on Computers and Accessibility (ASSETS'09), 2009
  4. L. Gagnon, S. Foucher, M. Héritier, M. Lalonde, D. Byrns, C. Chapdelaine, J. Turner, S. Mathieu, D. Laurendeau, N. T. Nguyen, D. Ouellet, Towards Computer-Vision Software Tools to Increase Production and Accessibility of Video Description to Visually-Impaired People, Universal Access in the Information Society, Springer-Verlag, 2009
  5. L. Gagnon, Automatic detection of visual elements in films and description with a synthetic voice - Application to video description, International Conf. on Low Vision, Montréal, 2008
  6. C. Chapdelaine, V. Gouaillier, M. Beaulieu, L. Gagnon, Improving Video Captioning for Deaf and Hearing-impaired People Based on Eye Movement and Attention Overload, IS&T/SPIE Symposium on Electronic Imaging: Human Vision & Electronic Imaging (SPIE #6492), San Jose, 2007
  7. C. Chapdelaine, M. Beaulieu, L. Gagnon, Vers une synchronisation du sous-titrage en direct franais avec les mouvements de limage, Interaction Homme-Machine, Montréal, 2006
  8. L. Gagnon, S. Foucher, F. Laliberté, M. Lalonde, M. Beaulieu, Towards an Application of Content-Based Video Indexing to Computer-Assisted Descriptive Video, Computer and Robot Vision, Quebec, 2006

Human-Computer Interaction

  1. P. D. Z. Varcheie, C. Chapdelaine, L. Gagnon, Infrared-Based Facial Points Tracking and Action Units Detection in Context of Car Driving Simulator, EURASIP Journal on Image and Video Processing 2012, 2012:15 doi:10.1186/1687-5281-2012-15
  2. P. D. Z. Varcheie, L. Gagnon, Lip Tracking Using Adaptive Fuzzy Particle Filter in the Context of Car Driving Simulator Under Low Contrast Near-Infrared Illumination, IEEE Int. Conf. on Acoustics, Speech and Signal Processing (ICASSP) 2010
  3. M. Lalonde, D. Byrns, L. Gagnon, N. Teasdale, D. Laurendeau, Real-time eye blink detection with GPU-based SIFT tracking, International Workshop on Video Processing and Recognition, 4th Canadian Conference on Computer and Robot Vision, Montréal, 2007
  4. C. Chapdelaine, S. Foucher, L. Gagnon, Impact of Gaze Analysis on the Design of a Caption Production Software, 13th International Conference on Human-Computer Interaction (HCI International 2009), 2009
  5. C. Chapdelaine, M. Beaulieu, L. Gagnon, Designing caption production rules based on face, text, and motion detection, IS&T/SPIE Symposium on Electronic Imaging: Human Vision & Electronic Imaging (SPIE #6806), San Jose, 2008
  6. L. Gagnon, S. Foucher, F. Laliberté, G. Boulianne, A Simplified Audio-Visual Fusion Model with Application to Large Vocabulary Recognition of French Canadian Speech, IEEE Can. Journal of Electrical and Computer Engineering, Vol. 33, No. 2, 2008
  7. S. Beauchemin, P. D. Z. Varcheie, L. Gagnon, D. Laurendeau, M. Lavallière, T. Moszkowicz, F. Prel, N. Teasdale, COBVIS-D: A Computer Vision System for Describing the Cephalo-Ocular Behavior of Drivers in a Driving Simulator, International Conference on Image Analysis and Recognition (ICIAR 2009), Halifax, 2009
  8. S. Foucher, F. Laliberté, G. Boulianne, L. Gagnon, A Dempster-Shafer Based Fusion Approach for Audio-Visual Speech Recognition with Application to Large Vocabulary French Speech, ICASSP, Toulouse, 2006

Remote Sensing

  1. M. Beaulieu, S. Foucher, L. Gagnon, Multispectral Image Resolution Refinement using Stationary Wavelet Transform with Marginal and Joint Statistics Modeling, 25ième Symposium Canadien sur la Télédétection/12ième Congrès de l'Association Québécoise de Télédétection, Montréal, 2003
  2. K. Rousseau, G. B. Bénié, L. Gagnon, Prédiction des performances et détecteur de contours adaptatif, 25ième Symposium Canadien sur la Télédétection/12ième Congrès de l'Association Québécoise de Télédétection, Montréal, 2003
  3. M. Beaulieu, S. Foucher, L. Gagnon, Multispectral Image Resolution Refinement using Stationnary Wavelet Transform, IGARSS, Toulouse, 2003
  4. P. Bugnet, F. Cavayas, L. Gagnon, Vers la cartographie automatisée des surfaces boisées en milieu urbain fondée sur la texture d'images IKONOS panchromatiques (le cas de la Région Métropolitaine de Montréal), Can. Jour. Remote Sensing, Vol. 29, No. 6, p. 755-769, 2003
  5. L. Gagnon, P. Bugnet, F. Cavayas, Texture-based segmentation of temperate-zone woodlands in panchromatic Ikonos imagery, SPIE Aerosense: Geo-Spatial Image and Data Exploitation Developments and Applications IV, (SPIE #5097), Orlando, 2003
  6. S. Allen, L. Gagnon, F. Lesage, Hydrous Area Segmentation in Radar Imagery by Level Set-Based Snakes, 10ième Congrès de l'Association Québécoise de Télédétection, Québec, 2001
  7. F. Lesage, L. Gagnon, Experimenting Level Set-Based Snakes for Contour Segmentation in Radar Imagery, SPIE Aerosense: Visual Information Processing IX (SPIE #4041), Orlando, 2000
  8. E. Aitnouri, S. Wang, D. Ziou, J. Vaillancourt, L. Gagnon, Estimation of a Multi-Modal Histogram's pdf Using a Mixture Model, Neural, Parallel and Scientific Computations, No. 7, p. 103-118, 1999
  9. D. McReynolds, P. Marchand, Y. Sheng, L. Gagnon, L. Sévigny, Stabilization of infrared image sequence with differential invariants and M-estimators, SPIE Aerosense: Acqusition, Tracking and Pointing XII (SPIE #3692), Orlando, 1999
  10. D. McReynolds, P. Marchand,Y. Sheng, L. Sévigny, L. Gagnon, Stabilization of infra-red aerial image sequences using robust estimation, Vision Interface, Trois-Rivières, 1999
  11. A. Jouan, P. Valin, L. Gagnon, E. Bossé, Airborne Fusion of Imaging and Non-Imaging Sensor Information for Maritime Surveillance, QCAV, Trois-Rivières, 1999
  12. E. Aitnouri, S. Wang, D. Ziou, J. Vaillancourt, L. Gagnon, An Algorithm for Determination of the Number of Modes for pdf Estimation of Multi-Modal Histograms, Vision Interface, Trois-Rivières, 1999
  13. L. Gagnon, Wavelet Filtering of Speckle Noise - Some Numerical Results, Vision Interface 1999, Trois-Rivières, 1999
  14. Y. Sheng, X. Yang, D. McReynolds, Z. Zhang, L. Gagnon, L. Sévigny, Real-world Multisensor Image Alignment Using Edge Focusing and Hausdorff Distance, SPIE Aerosense: Sensor Fusion - Architectures, Algorithms and Applications III (SPIE #3719), Orlando, 1999
  15. D. McReynolds, Y. Sheng, L. Gagnon, L. Sévigny, Stabilization of infrared image sequence with rotation, scaling and view angle changes, International Conference on Applications of Photonic Technology III, Ottawa, 1998
  16. L. Gagnon, H. Oppenheim, P. Valin, R&D activities in airborne SAR image processing/analysis at Lockheed Martin Canada, International Conference on Applications of Photonic Technology III, Ottawa, 1998
  17. A. Jouan, L. Gagnon, E. Shahbazian, P. Valin, Fusion of imagery attributes with non-imaging sensor reports by truncated Dempster-Shafer evidential reasoning, FUSION, Las Vegas, 1998
  18. P. Valin, L. Gagnon, M. Macieszczak, E. Shahbazian, E. Bossé, Testbed architecture for fusion of imaging and non-imaging airborne sensors, IGARSS, Seattle, 1998
  19. L. Gagnon, R. Klepko, Hierarchical classifier design for airborne SAR images of ships, SPIE Aerosense: Automatic Target Recognition V, Orlando, 1998
  20. E. Shahbazian, E. Bossé, L. Gagnon, M, Macieszczak, P. Valin, Multi-Agent Data Fusion Workstation (MADFW) Architecture, SPIE Aerosense: Sensor Fusion, Architetures, Algorithms and Applications II (SPIE #3376), Orlando, 1997
  21. H. Osman, L. Pan, S. Blostein, L. Gagnon, Classification of ships in airborne SAR imagery using backpropagation neural networks, SPIE Annual Meeting: Radar Processing, Technology and Applications II (SPIE #3161), San Diego, 1997
  22. V. Gouaillier, L. Gagnon, Ship silhouette recognition using principal components analysis, SPIE Annual Meeting: Applications of Digital Image Processing XX, (SPIE #3164), San Diego, 1997
  23. L. Gagnon, A. Jouan, Speckle filtering of SAR images - A comparative study between complex-wavelet-based and standard filters, SPIE Annual Meeting: Wavelet Applications in Signal and Image Processing V (SPIE #3169), San Diego, 1997
  24. E. Shahbazian, L. Gagnon, J.-R. Duquet, M. Macieszczak, P. Valin, Fusion of imaging and non-imaging data for surveillance aircraft, SPIE Aerosense: SensorFusion - Architecture, Algorithms and Applications (SPIE #3067), Orlando, 1997
  25. E. Shahbazian, E. Boily, L. Gagnon, P. Valin, Data Fusion Application for Surveillance Aircraft, Proceeding of the Conference Solutioneering '96 - A Lockheed Martin Technology Symposium, Valley Forge, 1996
  26. L. Gagnon, F. Drissi-Smaili, Speckle noise reduction of airborne SAR images with symmetric Daubechies wavelets, SPIE Aerosense: Signal and Data Processing of Small Targets (SPIE #2759), 1996

Medical Image Processing

  1. F. Laliberté, L. Gagnon, Studies on Registration and Fusion of Retinal Images, chapter 3 in Multi-Sensor Image Fusion and its Applications, Rick S. Blum and Z. Liu Eds., Taylor & Francis CRC Press, 2006
  2. F. Laliberté, L. Gagnon, Y. Sheng, Three-dimensional visualization of human fundus from a sequence of angiograms, IS&T/SPIE 17th Annual Symposium on Electronic Imaging: SPIE Stereocopic Displays and Applications XVI (SPIE #5664), San Jose, 2005
  3. L. Gagnon, F. Laliberté, M. Lalonde, R&D Activities in Retinal Image Analysis at CRIM, CMBES, Québec, 2004
  4. M. Lalonde, F. Laliberté, S. Foucher, L. Gagnon, RetsoftPlus: A Tool for Retinal Image Analysis, CBMS, Washington DC, 2004
  5. S. Foucher, M. Lalonde, L. Gagnon, Software for Automatic Detection and Monitoring of Fluorescent Lesions on Mice, CBMS 2004, Washington DC, 2004
  6. F. Laliberté, L. Gagnon, Y. Sheng, Registration and Fusion of Retinal Images: An Evaluation Study, IEEE Trans. Med. Imaging, Vol. 22, No. 5, p. 661-673, 2003
  7. F. Laliberté, L. Gagnon, Y. Sheng, Registration and Fusion of Retinal Images: A Comparative Study, International Conference on Pattern Recognition, Québec, 2002
  8. M. Lalonde, L. Gagnon, Variable Neighborhood Search for Geometrically Deformable Templates, International Conference on Pattern Recognition, Québec, 2002
  9. G. Yang, L. Gagnon, S. Wang, M.-C. Boucher, Algorithm for Detecting Micros-Aneurysms in Low Resolution Color Retinal Images, Vision Interface, Ottawa, 2001
  10. M. Lalonde, M. Beaulieu, L. Gagnon, Fast and Robust Optic Disk Detection Using Pyramidal Decomposition and Hausdorff-based template Matching, IEEE Trans. Med. Imaging, Vol. 20, No. 11, 1193-1200, 2001
  11. G. Yang, L. Gagnon, S. Wang, M.-C. Boucher, Algorithm for Detecting Micros-Aneurysms in Low Resolution Color Retinal Images, Vision Interface, Ottawa, 2001
  12. M. Lalonde, L. Gagnon, M.-C. Boucher, Automatic Image Quality Assessment in Optical Fundus Images, Vision Interface, Ottawa, 2001
  13. L. Gagnon, M. Lalonde, M. Beaulieu, M.-C. Boucher, Procedure to Detect Anatomical Structures in Optical Fundus Images, SPIE Medical Imaging: Image Processing (SPIE #4322), San Diego, 2001
  14. M. Lalonde, L. Gagnon, M.-C. Boucher, Non-recursive paired tracking for vessel extraction from retinal images, Vision Interface, Montréal, 2000
  15. L. Gagnon, J. M. Lina, B. Goulard, Sharpening enhancement of digitized mammograms with complex symmetric Daubechies wavelets, IEEE International Conference of Engineering in Medicine and Biology Society, Montréal, 1995
  16. J. M. Lina, L. Gagnon, Image enhancements with symmetric Daubechies' wavelets, SPIE Aerosense: Wavelet Applications in Signal and Image Processing III, Proc. SPIE #2569, Orlando, 1995

Nonlinear Wave Propagation & Optics

  1. R. Black, L. Gagnon, Optical Waveguide Modes: Polarization, Coupling and Symmetry, McGraw-Hill, 176 pages, 2010
  2. L. Gagnon, J. M. Lina, B. Goulard, Application of complex Daubechies' wavelets to numerical simulation of a nonlinear signal propagation model, IEEE Signal Processing Workshop on Statistical Signal and Array Processing, Qubec, 1994
  3. L. Gagnon, J. M. Lina, Symmetric Daubechies' wavelets and numerical solutions of NLS equations, J. Phys. A: Math. Gen. 27, 8207-8230, 1994
  4. L. Gagnon, N. Stiévenart, N-Soliton interaction in optical fibers; the multiple pole case, Opt. Lett. 19, 619-620, 1994
  5. L. Gagnon, Soliton on a CW background and collision between two dark pulses: some analytical results, J. Opt. Soc. Am. B 10, 469-474, 1993
  6. R. J. Black, J. Bures, L. Gagnon, Les modes caméléons des fibres et coupleurs optiques: effets de polarisation et de transition, Optique guide et photonique II, 60ime Congrs de l'ACFAS, Univ. de Montréal, p. 109-120, 1992
  7. L. Gagnon, P. A. Bélanger, Amplification homogne d'impulsions lumineuses dans un milieu dispersif non-linaire, Optique guide et photonique II, 60ime congrs de l'ACFAS, Univ. de Montréal, p. 131-135, 1992
  8. C. Paré, L. Gagnon, P. A. Bélanger, Aspherical laser resonators: an analogy with quantum mechanics, Phys. Rev. A 46, 4150-4160 (1992)
  9. L. Gagnon, C. Paré, Linear and nonlinear gaussian modes and their connection to conformal symmetry, Workshop on Nonlinear and Chaotic Phenomena, Univ. of Alberta, Edit. W. Rozmus et J. A. Tuszynski, World Scient. Publ., p. 90-93, 1991
  10. L. Gagnon, P. A. Bélanger, Adiabatic amplification of optical solitons, Phys. Rev. A 43, 6187-6193, 1991
  11. L. Gagnon, C. Paré, Nonlinear radiation modes connected to parabolic graded-index profile by the lens transformation, J. Opt. Soc. Am A 8, 601-607, 1991
  12. L. Gagnon, Quelques solutions exactes la thorie d'auto-focalisation optique obtenues par la méthode de réduction par symétries, Annual Seminar of the Canadian Mathematical Society on Lie Theory, Differential Equations and Representation Theory, Univ. de Montréal, Edit. V. Hussin, Les Publications CRM, p. 171-179, 1990
  13. L. Gagnon, Some exact solutions for optical wave propagation including transverse effects, J. Opt. Soc. Amer. B 7 (special issue: Transverse effects in nonlinear-optical systems, 1098-1102, 1990
  14. L. Gagnon, Similarity properties and nonlinear effects on optical precursors, Phys. Lett. A 148, 452-456, 1990
  15. L. Gagnon, P. A. Bélanger, Soliton self-frequency shift versus galilean-like symmetry, Opt. Lett. 15, 466-468, 1990
  16. R. J. Black, A. Hénault, L. Gagnon, F. Gonthier, S. Lacroix, Intensity-dependent few-mode lightguide interferometry, Optical Society of America Meeting on Nonlinear Guided-Wave Phenomena: Physics and Applications, Houston, p. 66-69, 1989
  17. C. Paré, L. Gagnon, P. A. Bélanger, Self-trapping in a weakly saturated amplifying/absorbing medium, Opt. Comm. 74, 228-232, 1989
  18. L. Gagnon, Exact traveling wave solutions for optical models based on the nonlinear cubic-quintic Schrdinger equation, J. Opt. Soc. Amer. A 6, 1477-1483, 1989
  19. P. A. Bélanger, L. Gagnon, C. Paré, Solitary pulses in nonlinear amplifying medium, Opt. Lett. 14, 943-945 (1989)
  20. L. Gagnon, R. J. Black, Fibres à coeurs multiples et gaine finie,9ièmes journées nationales d'optique guidée, Lannion, p. 34-35, 1988

Symmetry Groups of Differential Equations

  1. L. Gagnon, P. Winternitz, Symmetry classes of variable coefficient nonlinear Schrödinger equations, J. Phys. A: Math. Gen. 26, p. 7061-7076, 1993
  2. M. Kovalyov, M. Légaré, L. Gagnon, Reductions by isometries of the self-dual Yang-Mills equations in four-dimensional Euclidean space, J. Math. Phys. 34, p. 3245-3268, 1993
  3. M. Kovalyov, M. Légaré, L. Gagnon, Self-dual Yang-Mills equations reduced by subgroups of E(4), 19th Intern. Colloquium on Group Theoretical Methods in Physics, Salamanca,, World Scient. Publ., 1992
  4. L. Gagnon, Self-similar solutions for a coupled system of nonlinear Schrödinger equations, J. Phys. A: Math. Gen. 25, p. 2649-2667 (1992)
  5. M. Florjanczyk, L. Gagnon, Radiative-like solutions of the Eckhaus equation, Phys. Rev. A 45, p. 6881-6883 (1992)
  6. L. Gagnon, Localized self-similar structures for coupled NLS equations: an approximate analysis, 7th Interdisciplinary Workshop on Nonlinear Coherent Structures in Physics and Biology, Université de Bourgogne, Dijon, Edit. M. Remoissenet et M. Peyrard, Lecture Notes in Physics 393, Springer Verlag, p. 383-390, 1991
  7. L. Gagnon, P. Winternitz, Non-Painlev reductions of nonlinear Schrödinger equations, Phys. Rev. A 42, p. 5029-5030, 1990
  8. J. Beckers, L. Gagnon, V. Hussin, P. Winternitz, Superposition formulas for nonlinear super-equations, J. Math. Phys. 31, p. 2528-2534, 1990
  9. M. Florjanczyk, L. Gagnon, Exact solutions for a higher-order nonlinear Schrödinger equation, Phys. Rev. A 41, p. 4478-4485, 1990
  10. L. Gagnon, Equation of motion and wave functions in spherical coordinates for an integrable hamiltonian system, J. Math. Phys. 30, p. 313-317, 1989
  11. L. Gagnon, Continuous subgroups of the Galilei and Galilei-similitude groups, Can. J. Phys. 67, p. 1-25, 1989
  12. L. Gagnon, P. Winternitz, Exact solutions of the cubic-quintic nonlinear Schrödinger equation obtained by symmetry reduction, 17th International Colloquium on Group Theoretical Methods in Physics, Univ. de Montréal, Edit. Y. Saint-Aubin et L. Vinet, World Scient. Publ., p. 480-483, 1989
  13. V. Hussin, J. Beckers, L. Gagnon, P. Winternitz, Nonlinear equations with superposition principles; the Lie group G2 and its maximal subgroups, 17th Intern. Colloquium on Group Theoretical Methods in Physics, Univ. de Montréal, Edit. Y. Saint-Aubin et L. Vinet, World Scient. Publ., p. 492-495, 1989
  14. L. Gagnon, B. Grammaticos, A. Ramani, P. Winternitz, Lie symmetries of a generalised nonlinear Schrödinger equation III - Reductions to third order ordinary differential equations, J. Phys. A: Math. Gen. 22, p. 499-509, 1989
  15. L. Gagnon, P. Winternitz, Lie symmetries of a generalised nonlinear Schrödinger equation II - Exact solutions, J. Phys. A: Math. Gen. 22,4 p. 69-497, 1989
  16. L. Gagnon, P. Winternitz, Exact solutions of the cubic and quintic nonlinear Schrödinger equation for a cylindrical geometry, Phys. Rev. A 39, p. 296-306, 1989
  17. L. Gagnon, P. Winternitz, Exact solutions of the spherical quintic nonlinear Schrödinger equation, Phys. Lett. A 134, p. 276-281, 1989
  18. L. Gagnon, V. Hussin, P. Winternitz, Nonlinear equations with superposition formulas and the exceptional group G2 III - The superposition formulas, J. Math. Phys. 29, p. 2145-2155, 1988
  19. L. Gagnon, P. Winternitz, Lie symmetries of a generalized nonlinear Schrödinger equation I - The symmetry group and its subgroups, J. Phys. A: Math. Gen. 21, p. 1493-1511, 1988
  20. L. Gagnon, J. Beckers, V. Hussin, P. Winternitz, Nonlinear differential equations with superposition laws for the ops(1,2) superalgebra, 15th International Colloquium on Group Theoretical Methods in Physics, Drexel Univ. , Philadelphia, Edit. R. Gilmore, World Scient. Publ., p. 435-438, 1987
  21. J. Beckers, L. Gagnon, V. Hussin, P. Winternitz, Nonlinear differential equations and Lie superalgebras, Lett. Math. Phys. 13, p. 113-119, 1987
  22. L. Gagnon, J. Harnad, J. Hurtubise, P. Winternitz, Abelian integrals and the reduction method for an integrable hamiltonian system, J. Math. Phys. 26, p. 1605-1612, 1985
  23. L. Gagnon, J. Harnad, P. Winternitz, Group projection method and the separation of variables for an integrable hamiltonian system, 13th International Colloquium on Group Theoretical Methods in Physics, Maryland Univ., Washington, Edit. W. W. Zachary, World Scient. Publ., p. 123-126, 1984