Renée Elio
Department of Computing Science
University of Alberta
Edmonton, Alberta T6G 2H1
email: ree@cs.ualberta.ca
Grants Publications Students/PDFs
Education Graduate Studies
Yale University 1977-1978
Carnegie-Mellon University 1978- 1981.  Ph.D. awarded 1981

Undergraduate Studies
Smith College 1973-1977.  B.A. awarded, Magna Cum Laude, with Honors 1977

Current Position Professor and Associate Dean (Research), Faculty of Science
Department of Computing Science, 1985-

University of Alberta
Edmonton, Alberta, Canada
Previous Positions Research Scientist, 1983-1985
Alberta Research Council,
Edmonton, Alberta, Canada

Information and Decision Sciences Group, 1981-1983
Bell Laboratories
Whippany, New Jersey  USA
Board Appointments Board of Directors, Government of Alberta Information and Communications Technology Institute, 2006-2009. The Institute's board provides strategic advice and policy recommendations and sets priorities for research investment for Alberta in information and communications science and technology, broadly defined. Board of Directors, Alberta Research Council, 1988-1994
Board of Directors, Edmonton Council for Advanced Technology, 1992-1993
Courtesy Appointments Visiting Scholar, Center for the Study of Language and Information, Stanford University, 1997-1998
Visiting Scholar, Department of Epidemiology, University of Washington, Seattle. 1990-1991
Adjunct Professor, Department of Computer Science, University of Calgary, 1984-1987
Research Areas Interdisciplinary studies and computational models of human and machine reasoning, particularly intention representation and executive control, belief revision, problem solving, and skill acquisition; models of software agent communication. Industrial Contracts and Consulting Daimler-Benz Research and Technology North America, Palo Alto, California, 1997-1998
Consulting member of the Adaptive Systems Group on projects for intelligent driver-assistant software.

AGT Limited (now Telus Communications), Edmonton, Alberta, 1993-1994
Consultant on AI learning methods vs. statistical analysis methods for telecommunication applications.

AGT Limited (now Telus Communications), Edmonton, Alberta, 1989 -1990
Consultant on expert systems design and implementation; high level specification and project planning documents; scientific consultation and program evaluation for a $1 million technology transfer program on applied AI.

Synerlogic, Inc., Calgary, Alberta, 1986
Knowledge engineering and consulting for design and implementation of a system to provide instructional design advice for developing computer-based training material.

Interact Research & Development, (now Acquired Intelligence) Victoria, British Columbia 1985
Contract development for applied AI systems.

Research Grants (all amounts are in Canadian dollars, net without overhead) 2002 NSERC Individual Research Grant: $108,000
      Title: Information analysis in electronic archives and in agent communication
2000-2003 CFI (Co-investigator with three others): $614,000
      Title: An Infrastructure for electronic publishing and analysis of humanities source material
1998 NSERC Individual Research Grant: $100,430
      Title: Interdisciplinary studies of non-monotonic reasoning and learning
1994 NSERC Individual Research Grant : $88,000
      Title: Interdisciplinary studies of non-monotonic reasoning and learning
1994 NSERC Equipment Grant (with F. J. Pelletier): $15,600
      Title: Cognitive Science Laboratory Equipment
1994 NSERC Infrastructure Grant (with 6 others): $133,000
      Title: AI/Database/Software Engineering Labs
1993 University of Alberta Central Research Fund: $5,000
      Title: AI-94 Conference
1993 Central Research Fund Grant (with F.J. Pelletier): $3,200
      Title: Investigations of Default Reasoning
1991 NSERC Infrastructure Grant (with 8 others): $135,00
      Title: Artificial Intelligence-Robotics Vision Group.
1990 NSERC Individual Research Grant: $84,000
      Title: Computational Models of Learning
1990 NSERC Research Infrastructure Grant (with 4 others): $40,000
      Title: AI and Robotics Infrastructure.
1988 NSERC Infrastructure Research Grant (with 4 others): $90,000
      Title: AI and Robotics Infrastructure.
1987 NSERC Individual Research Grant: $63,000
      Title: Machine Learning and Knowledge-based Systems.
1986 NSERC Individual Research Grant: $19,000
      Title: Knowledge-based Systems Representations.
1985 NSERC Individual Research Grant: $15,140
      Title: Interdisciplinary Research on Knowledge-based Systems.
Service to the Profession
    Invited Chair and Organizer, Eleventh Vancouver Studies in Cognitive Science Symposium, Simon Fraser University, February, 1998.
    Vice-President, Canadian Society of Computational Studies of Intelligence, 1996-1998.
    Program Chair, 1994 National Conference of the Canadian Society for Computational Studies of Intelligence, Banff, Alberta.
    Editor, 1994 Proceedings of the National Conference of the Canadian Society for Computational Studies of Intelligence.
    Invited discussant and coordinator for a one-day video conference on artificial intelligence presented by the IEEE Northern Alberta Chapter, October, 1986.
    Program committee member for various conferences and ad hoc reviewer for  journals and conference proceedings, including IJCAI, Cognitive Science Conference, Machine Learning, IEEE Transactions on Pattern Analysis and Machine Intelligence, Computational Intelligence, Journal of Experimental Psychology: Human Learning and Memory; Cognitive Psychology, Cognitive Science.
    Ad hoc reviewer, NSERC grants, NSF grants.
Service to the University of Alberta
University
2007-20011 University of Alberta Academic Plan Development; Campus Law Review, 2000-2003; Member, Committee to define Humanities Computing MA degree(2000); Member, Humanities Computing recruitment and hiring committee (2001); General Faculties Council Standing Committee: Undergraduate Scholarships Committee (1999-2003); Faculty of Graduate  Studies and Research Unit Review for Department of Linguistics (1998); General Faculties Council Member (1992-1996); Ad hoc committee for Vice-President (Research) on attracting and retaining university scholars (1989); General Faculties Council Killam Memorial Chair Selection Committee (1988-89); Founding Member and  Executive Committee Member, Alberta Centre for Machine Intelligence and Robotics (1986-1990).

Faculty of Science
Associate Dean (Research); Department of Computing Science Chair Review and Selection,( 2002-2003); Faculty Evaluation Committee (1998-2000); Faculty of Science Representative on Faculty of Rehabilitation Medicine Council (1998-2000); Appeals Committee on Academic Standing (1988-89, 1991-93); Faculty of Science Representative on Faculty of Business Council (1994-1996).

Department of Computing Science
Acting Chair (Jan 2004-July 2004); Associate Chair (Undergraduate) (2000- );Associate Chair (Graduate) and Chair of Graduate Admissions Committee (1999-2000); Curriculum Committee (1998-1999); Curriculum Liaison with Grant MacEwan Community College (1999); Faculty Recruiting Committee, (1996-1997); Director of Undergraduate Programs (1991-1994.); Executive Committee (1986-1987; 1988-89; 1991-1994); Graduate Admissions Committee (1986-1988); Faculty Selection Committee (1985-1986); Task Force on Teaching Evaluation and Teaching Assistants (1985-87, 1989).

Service to the Community Prospects Literacy Association, Edmonton, Adult Literacy Tutor  (1998); High School and Grammar School presentations on technology and computer science careers: J. Percey Page School (Nov. 1992); Westglenn Elementary School (Jan. 1993); Ecole Secondaire Ste. Marguerite D. Youville, St. Albert (Feb. 1994)

Invited newspaper, radio, and TV interviews: Edmonton Journal "Science and Health" feature article on METEOR expert system (June, 1986); TV program for ACCESS TV's "Discovery Digest," (Fall, 1986); Radio spots for Edmonton Radio CKUA Science Digest Series (1986).

"About Artificial Intelligence." Invited session given at "Confronting Technophobia" conference, organized by the Association for the Advancement of Science in Canada and the University of Alberta Committee on Women in Scholarship, Engineering, Science, and Technology. University of Alberta, May, 1986.

Papers and Publications

Elio, R. (2006). On Modeling Intentions for Prospective Memory Performance. In Proceedings of the 28th Annual Conference of the Cognitive Science Society, 1269-1274. July 26-29, Vancouver, Canada. Brown, S., Clements, P., Elio, R., & Grundy, I. (2005).Between markup and delivery: Tomorrow's electronic text today. In R. Siemens (Ed.), Mind Technologies, 15-32. University of Calgary Press. pdf-file Blanchet, W., Elio, R., & Stroulia, E. (2005) Conversation errors in web service coordination: run-time detection and repair. In Proceedings of the 2005 IEEE/WIC/ACM International Joint Conference on Web Intelligence and Intelligent Agent Technology, 442-449. September 19-22, Compiegne University of Technology, France. pdf-file

Blanchet, W., Stroulia, E., & Elio, R. (2005) Supporting adaptive web-service orchestration with an agent conversation framework. In Proceedings of the 2005 IEEE International Conference on Web Services, 541-549. July 11-15, Orlando, USA. pdf-file

Neouchi, R., Elio, R., & Zhang, H. (2005). Distance based communication in a surveillance task in a multi-robot system. In The 2005 IEEE/JRS International Conference on Intelligent Robots and Systems, 221-227. Edmonton, Canada.

Pelletier, F.J., & Elio, R. (2005) The case for psychologism in default reasoning, Synthese, 146, 7-35.pdf-file

Elio, R. & Petrinjak, A. (2005). Normative communication models for agent error messages. Autonomous Agents and Multi-Agent Systems, 11, 273-305. pdf-file

Brown, S., Grundy, I., Clements, P., Elio, R., Balazs, S., & Cameron, R. (2004). Intertextual Encoding in the Writing of Women's Literary History. Computers and the Humanities 38, 191-206.

Bac, M. & Elio, R. (2004). Schema-based alethic realism: Agency, the environment, and truthmaking. Minds and Machines, 14, 173-196 . pdf-file

Pelletier, F. J., & Elio, R. (2003). Enumerating the preconditions of agent message types. In Y. Xiang and B. Chaib-draa (Eds.) Advances in Artificial Intelligence: Proceedings of the 16th Conference of the Canadian Society for Computational Studies of Intelligence, LNAI 2671, 50-65. Springer-Verlag, Berlin. pdf-file Petrinjak, A., & Elio, R. (2003). Understanding "not-understood": Towards an ontology of error conditions in agent communication. In Y. Xiang and B. Chaib-draa (Eds.) Advances in Artificial Intelligence: 16th Conference of the Canadian Society for Computational Studies of Intelligence, LNAI 2671, 383 - 399. Springer-Verlag, Berlin. Pdf-file Elio, R. (ed.) (2002) Common sense, reasoning, and rationality.New York: Oxford University Press. Elio, R. (2002). Issues in common sense reasoning. In R. Elio (Ed.) Common sense, reasoning, and rationality. New York: Oxford University Press.pp 3-36.

Elio, R. (2002). Belief-desire-intention agency in a general cognitive architecture. Cognitive Science Quarterly, 2, 321-340.

Pelletier, F.J., & Elio, R. (2002) Logic and Computation. In P. Gardenfors, K. Kijania-Placet, J. Wolenski (Eds) Scope of Logic, Methodology and Philosophy of Science, Vol. 1, Synthese Library #315, 137-156. Dordrecht: Kluwer Academic Press. Pdf-file

Elio, R., Haddadi, A., & Singh, A. (2000). Task models, intentions, and agent communication. Lecture Notes in Artificial Intelligence 1886: Proceedings of the Pacific Rim Conference on AI (PRICAI-2000), 394-403. Springer Verlag: Berlin pdf-file

Elio, R. , Haddadi, A., & Singh, A. (2000) Task models for agent conversation policies. Proceedings of Autonomous Agents-2000, 229-230. Pdf-file.

Upal, M.A. & Elio, R (2000).  Learning rewrite rules versus search control rules to improve plan quality. Proceedings of the  Canadian Conference on Artificial Intelligence, pp. 240-253. June, 2000. Pdf-file

Upal, M. A. & Elio, R. (1999). Learning rationales to improve plan quality for partial order planners.  In A. Kumar & I. Russell (Eds.) Proceedings of the Twelfth International  FLAIRS Conference, pp. 371-377 Orlando, Florida.  AAAI Press: Menlo Park, CA. Pdf-file

Elio, R. & Haddadi, A (1999). Abstract tasks and conversation policies. In F. Dignum & M. Greaves (Eds.) Issues in Agent Communication, 301-314. Springer Verlag, Berlin pdf-file

Langley, P. , Thompson C., Elio, R., & Haddadi, A. (1999).  An adaptive conversational interface for destination advice. In M. Klusch, O. Shehory, and G. Weiss (Eds.) Cooperative Informational Agents III, Springer Verlag, Berlin, pp. 347-364. Pdf-file

Pelletier, F. J. & Elio, R (1999). A study of belief revision theories. In J. Wiles  & T. Dartnell (Eds). Perspectives on Cognitive Science II. Ablex Publishing, New Jersey, pp.131-148.

Elio, R. & Haddadi, A. (1999). On abstract tasks and conversation policies. In M. Greaves & J. Bradshaw (Eds.) Specifying and Implementing Conversation Policies for Agents, pp. 89-98. Third International Conference on Autonomous Agents. Seattle, Washington. Menlo Park, CA: AAAI Press.

Upal, M. A. & Elio, R. (1998). Learning to improve the quality of plans produced by partial-order planners. In A. Valente (Ed.) Knowledge Engineering and Acquisition for Planning Workshop Papers, (pp. 94-113). Fourth International Conference on Artificial Intelligence Planning Systems. AAAI Technical Report. Menlo Park, CA:AAAI Press. Pdf-file

Elio, R. (1998). How to disbelieve p-> q: Resolving contradictions. In Proceedings of the Twentieth Annual Conference of the Cognitive Science Society, pp. 315-320. University of Wisconsin, Madison.  Lawrence Erlbaum Associates: New Jersey. Pdf-file

Elio, R. & Pelletier, F. J. (1997). Belief change as propositional update. Cognitive Science, 4, 419-460.

Pelletier, F.J. & Elio, R. (1997). What should default reasoning be, by default? Computational Intelligence, 13, 165-187. Pdf-file

Elio, R. (1997). Generating alternative process models through simulation. In B. Endres-Niggemeyer & C. Inchaurralde (Eds.) The cognitive level. Duisburg, Netherlands: Linguistic Agency University of Duisburg.

Elio, R. (1997). Broken promises and disabled causes: On the epistemic entrenchment of conditionals in belief revision. Proceedings of the 1997 International Conference on Artificial Intelligence(IJCAI-97), p. 34. Nagoya, Japan.

Elio, R. (1997). Separating computer skills from computer science: The evolution of computing courses at the University of Alberta. In G. K. Tsiknis (Ed.) Proceedings of the Western Canadian Conference on Computing Education, pp. 35-48. Nanaimo, BC: British Columbia Computers in Education.

Elio, R. (1997). What to believe when inferences are contradicted: The impact of knowledge type and inference rule. In M. G. Shafto & P. Langley (Eds.), Proceedings of the Nineteenth Annual Conference of the Cognitive Science Society, pp. 211-216. Hillsdale, NJ: Lawrence Erlbaum Associates.pdf-file

Elio, R. & Pelletier, F.J. (1996). On reasoning with default rules and exceptions. In G. W. Cottrell (Ed.) Proceedings of the Eighteenth Annual Conference of the Cognitive Science Society, pp. 131-136. Hillsdale, NJ: Lawrence Erlbaum Associates. Pdf-file

Elio, R. & Lin, K. (1994). Simulation models of the influence of learning mode and training variance on category learning. Cognitive Science, 18, 185-220.

Elio, R. & Pelletier, F. J. (1994). On relevance in nonmonotonic reasoning: Some empirical studies. In R. Greiner & D.  Subramanian (Eds.), Relevance: American Association for Artificial Intelligence 1994 Fall Symposium Series, New Orleans, pp. 64-67. Menlo Park, CA: AAAI Press.

Elio, R. & Pelletier, F. J. (1994). The effect of syntactic form on simple belief revisions and updates. In A. Ram & K. Eiselt (Eds.), Proceedings of the Sixteenth Annual Conference of the Cognitive Science Society, pp. 260-266. Hillsdale, NJ: Lawrence Erlbaum Associates. Pdf-file

Elio, R. & Watanabe, L. (1993). Simulating interactive effects of domain knowledge and category structure with a constructive induction system. In Sloman, A., Hogg, P., Humphries, G., Ramsey, A., & Partridge, P. (Eds.) Prospects of Artificial Intelligence: Proceedings of the Biennial Conference of the Society for the Study of Artificial Intelligence and the Simulation of Behavior, pp. 250-260. Birmingham, UK: IOS Press.

Elio, R. & Pelletier, F.J. (1993). Human benchmarks on AI's benchmark problems. Proceedings of the 1993 Annual Cognitive Science Conference. pp. 406-411. Boulder, CO: Morgan Kaufmann.

Scharf, P.B., Sanger, V., & Elio, R. (1992). Corporate perspectives on technology transfer: An expert systems apprenticeship program. IEEE Expert, 7, 6-13.

Elio, R. & Watanabe, L. (1991). An incremental deductive strategy for controlling constructive induction in learning from examples. Machine Learning, 7, 7-44.

Elio, R. & Scharf, P.B. (1990). Modeling novice-to-expert shifts in problem solving strategy and knowledge organization, Cognitive Science, 14, 579-640.

Elio, R. deHaan, J. & Strong, G. (1987). METEOR: An intelligent system for storm forecasting. Invited paper for a special issue on artificial intelligence in Journal of Atmospheric and Oceanic Technology, 4, 19-28.

Watanabe, L. & Elio, R. (1987). Guiding constructive induction in learning by examples. Proceedings of the Tenth International Conference on Artificial Intelligence, pp. 293-296, Milan, Italy.

Elio, R. & deHaan, J. (1986). Representing and integrating qualitative and quantitative knowledge in a knowledge-based storm forecasting system. International Journal of Man-Machine Studies, 25, 523-547.

Elio, R. deHaan, J., & Strong, G. (1986). Combining statistical models and artificial intelligence for forecasting. Proceedings of the Workshop on Operational Meteorology, sponsored by the Atmospheric Environment Service and the Canadian Meteorological and Oceanographic Society, Winnipeg.

Elio, R. (1986). Representation of similar well-learned cognitive procedures. Cognitive Science, 10, 41-73.

Elio, R. & deHaan, J. (1985). Knowledge representation for a severe storm forecasting system. Proceedings of the Ninth International Joint Conference on Artificial Intelligence (ICJAI-85), pp. 401-409.

Elio, R. & Anderson, J.R. (1984). The effects of information order and learning mode on schema abstraction. Memory & Cognition, 12, 20-30.

Elio, R. & Healy, A.F. (1982). Deep structure syntactic relations: To-be-retrieved information and retrieval cues in prompted sentence recall. Language and Speech, 7, 397-417.

Elio, R. & Anderson, J.R. (1981). The effects of category generalizations and instance similarity on schema abstraction. Journal of Experimental Psychology: Human Learning and Memory, 7, 397-417.

Elio, R. E. & Reutener, D.B. (1978). Color context as a factor in encoding and as an organizational device for retrieval. Journal of General Psychology, 99, 223-232.

Other Publications Elio, R. (2000). Artficial Intelligence". Sub-heading under subject entry for "Computer Science." The Canadian Encyclopedia www.thecanadianencyclopedia.com

Elio, R. (1994). Editor, Proceedings of the National Canadian Conference on Artificial Intelligence, Banff, Alberta. 320 pp.

Elio, R. (1987).  AI at the University of Alberta. Canadian Artificial Intelligence Magazine, April, 1987 pp. 27-29.

Major Reports and Papers for Industry Elio, R. & Haddadi, A. (1998). Dialogue Management for an Adaptive Database Assistant. Daimler-Benz Research and Technology North America, Technical Report 3-1998. Palo Alto, California. 44 manuscript pages.

Elio, R. (1990). Expert Systems Apprenticeship Program: Evaluation Report. AGT (Telus) Communications Technical Report TR-085-203-90-001, Edmonton, Alberta. 73 manuscript pages. (This work served as the basis for the IEEE Expert article  cited above).

Selected Conference Presentations and Invited (*) Presentations * Cognitive architectures, rationality, and meta-reasoning. Twenty-fifth Annual Conference on the Philosophy of Science: Rationality and History of Science.  Dubrovnik, Croatia. 1999.

How to disbelieve p->q: Resolving contradictions.  Twentieth Annual Conference of the Cognitive Science Society, Wisconsin, Madison, 1998.

What to believe when inferences are contradicted:The impact of knowledge type and inference rule.  Nineteenth Annual Conference of the Cognitive Science Society, Stanford University, 1997.

On reasoning with default rules and exceptions. Eighteenth Annual Conference of the Cognitive Science Society, University of California at San Diego, 1996.

Studies of belief revision. Third Australasian Conference on Cognitive Science, Queensland University, Brisbane: April, 1995.

Methodological issues in cognitive simulation. Fourth International Colloquium on Cognitive Science, San Sebastián, Spain. 1995.

Human benchmarks on AI's benchmark problems. Sixteenth Conference of the Cognitive Science Society, 1993. University of Boulder, Colorado.

Relevance in Default Reasoning. Workshop on Relevance in Nonmonotonic Reasoning. IRIS. 1992 Kananaskis, Canada. (presented by F. J. Pelletier).

Psychological investigations into the nonmonotonic benchmarks. Seminar on Semantic Formalisms, 1993. Dagstuhl, Germany, sponsored by DFG and University of Saarbrueken (presented by F. J. Pelletier).

 Simulating interactive effects of domain knowledge and category structure with a constructive induction system. Conference of the Society for the Study of Artificial Intelligence and the Simulation of Behavior.  Birmingham, UK., 1992

* Intelligent Computer-Assisted Instruction Invited Tutorial Workshop for International Conference on Computer-Assisted Learning in Post-Secondary Education, Calgary. Sponsored by the University of Calgary and the Institute for Computer-Assisted Learning, University of Calgary, Alberta, 1985.

* About Artificial Intelligence. Invited session given at "Confronting Technophobia" conference, organized by the Association for the Advancement of Science in Canada and the University of Alberta Committee on Women in Scholarship, Engineering, Science, and Technology. University of Alberta, May, 1986.

* The METEOR system for severe storm forecasting. Invited presentation to the Artificial Intelligence Research in Environmental Conference, sponsored by the US National Oceanic and Atmospheric Administration (NOAA), Boulder, Colorado, May 1986.

Knowledge representation for a severe storm forecasting system. Ninth International Joint Conference on Artificial Intelligence, Los Angeles, CA: 1985.

* Invited discussant and coordinator for one day video conference on artificial intelligence, IEEE Northern Alberta Chapter, October, 1986.

Post Doctoral Fellows, Graduate and Honors Students J. Arnold. Research area: Modelling believeable synthetic agents
R. Neouchi. Research area: Agent communication.
D. Jung. Research Area: planning and intention.

W. Blancket, M.Sc. 2005. Enabling Automatic Recovery from Communication Failures between Composed Web Services.
A. Petrinjak, M.Sc. 2003. A model based approach to agent communication and communication error conditions. for coordinated agent problem solving and dialogue.

M. Taboada. 2000. PDF. Research Project: Models of dialogue for human and agent conversation.
A. Upal. Ph.D. 2000. Title:  Learning to improve plan quality for partial-order planners
S. Kremer. Ph.D. 1996. Title: A theory of grammatical induction in the connectionist paradigm
M. Carbonaro. M.Sc. 1995. Title: Biases in decision making: Implications for decision-support systems
W. Mah. M.Sc. 1996. Title: Statistical frameworks for default reasoning.
S. Madan. M.Sc. 1995. Title: Knowledge discovery from databases
C. Stafford. M.Sc. ( Co-supervisor, Electrical Engineering) 1991. Title: Intelligent circuit design
K.Lin. M.Sc, 1990. Title: Computer models of analytic and non analytic strategies for concept learning
P. Leung. M.Sc., 1989. Title: Abstracting and using domain relations to expedite concept learning
L. Watanabe. M.Sc., 1987. Title: Guiding constructive induction for incremental concept learning from examples
P. Scharf, M.Sc. 1987. Title: A computer model of knowledge organization and strategy shifts in novice-expert problem solving
J. Madrenus. Member of M.Sc. Committee to define Dr. Madrenus' program in Interdisciplinary Studies and his thesis in Medicine & Computer Science, 1988.
Teaching Experience Introduction to Computing and Computation (CMPUT 101): A first course for majors
Introduction to Computing Science (CMPUT 114) . A first course for majors.
Programming and Data Structures (CMPUT 115) . Second course for majors.
Undergraduate Honors Seminar (CMPUT 495). Seminar course for undergraduate honors students.
Artificial Intelligence (CMPUT 451). Advanced undergraduate course.
Artificial Intelligence (CMPUT 551). Graduate course.
Topics in Artificial Intelligence: Knowledge-based Systems. Graduate seminar.
Topics in Artificial Intelligence: Learning. Graduate seminar.
Agent architectures and agent communication. Graduate Seminar
Citizenship Dual citizenship: USA and Canada