I doubt that it will answer the question, but my chapter in the recent Cambridge
Handbook on Linguistic Code-Switching discusses some of the complexities of
this. The full reference is:

Sebba, Mark "On the notions of congruence and convergence in code-switching", in
Barbara E. Bullock and Almeida Jacqueline Toribio (eds) The Cambridge Handbook
on Linguistic Code-Switching, pp. 40-57. Cambridge University Press, 2009.

Mark

Dr Mark Sebba
Reader in Sociolinguistics and Language Contact
Department of Linguistics,
Lancaster University
Lancaster LA1 4YT
Great Britain
Tel. +44 1524 592453
Fax +44 1524 843085
e-mail: M.Sebba@...


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