On Comparison, Equivalence and Addition of Magnitudes


  • Paulo A. Veloso Federal University of Rio de Janeiro, UFRJ. CNPq.
  • Abel Lassalle-Casanave Federal University of Salvador de Bahia. CNPq.
  • Eduardo N. Giovannini Universidad Nacional del Litoral. CONICET.




A theory of magnitudes involves criteria for their comparison, equivalence and addition. We examine these aspects from an abstract viewpoint, stressing independence and definability. These considerations are triggered by the so-called De Zolt’s principle in the theory of equivalence of plane polygons.

Author Biographies

Paulo A. Veloso, Federal University of Rio de Janeiro, UFRJ. CNPq.

Professor of Federal University of Rio de Janeiro.

Abel Lassalle-Casanave, Federal University of Salvador de Bahia. CNPq.

Professor of Federal University of Salvador de Bahia

Eduardo N. Giovannini, Universidad Nacional del Litoral. CONICET.

Professor of Universidad Nacional del Litoral.


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