Aldrovandi, R. [UNESP]Kraenkel, Roberto André [UNESP]2014-05-272014-05-271989-12-01Journal of Mathematical Physics, v. 30, n. 8, p. 1866-1870, 1989.0022-2488http://hdl.handle.net/11449/130456The basic field equations of a field theory are not always derivable from a Lagrangian. Lagrangian theories are perturbatively coherent, in the sense that they have well-defined vertices. Non-Lagrangian theories may be coherent or not. Coherent theories are, in principle, quantizable by perturbative methods. The general condition for a theory to have well-defined vertices is given. © 1989 American Institute of Physics.1866-1870engArtigo10.1063/1.528273WOS:A1989AH02700026Acesso aberto2-s2.0-30430024272-s2.0-3043002427.pdf