< Order Theory

AB3, AB3*, AB5 and AB5* are actually due to von Neumann, but Grothendieck's name stuck.

Definition (AB3):

A preordered class is said to satisfy the third Grothedieck axiom AB3 iff for all families indexed over a set , a least upper bound exists.

Definition (AB3*):

A preordered class is said to satisfy the dual third Grothedieck axiom AB3* iff for all families indexed over a set , a greatest lower bound exists.

Definition (AB5):

A class of preordered sets is said to satisfy the fifth Grothendieck axiom AB5 if and only if for all and all families of elements of elements of and each element , we have

Definition (AB5*):

A class of preordered sets is said to satisfy the dual fifth Grothendieck axiom AB5* if and only if for all and all families of elements of elements of and each element , we have

Definition (AB6):

A class of preordered sets is said to satisfy the sixth Grothendieck axiom AB6 if and only if for all

This article is issued from Wikibooks. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.