Chainable and zero spans
by
Fernando Macías-Romero
Facultad de Ciencias físico Matemáticas de la Benemérita Universidad Autónoma de Puebla

In this talk we prove the following theorem: Let X₁ and X₂ be continua with zero surjective semispan (\sigma₀ ^* (X₁) = \sigma₀ ^* (X₂)=0). If Y₁ and Y₂ are continua and f₁: Y₁ --> X₁ and f₂: Y₂ --> X₂ are any two surjective mappings, then f₁ ×f₂: Y₁ ×Y₂ --> X₁ ×X₂ given by (f₁ ×f₂)(x₁, x₂) = (f₁(x₁), f₂(x₂)) is universal.

This is another result in which we can change chainability for zero span.

Date received: January 12, 2001

Copyright © 2001 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # cagh-03.