Title
The downward directed grounds hypothesis and very large cardinals.
Abstract
A transitive model M of ZFC is called a ground if the universe V is a set, forcing extension of M. We show that the grounds of V are downward set-directed. (Consequently, we establish some fundamental theorems on the forcing method and the set-theoretic geology. For instance, (1) the mantle, the intersection of all grounds, must be a model of ZFC. (2) V has only set many grounds if and only if the mantle is a ground. We also show that if the universe has some very large cardinal, then the mantle must, be a ground.
Year
DOI
Venue
2017
10.1142/S021906131750009X
JOURNAL OF MATHEMATICAL LOGIC
Keywords
Field
DocType
Forcing method,set-theoretic geology,downward directed grounds hypothesis,large cardinal,generic multiverse
Discrete mathematics,Large cardinal,Cardinal number,Mantle (geology),Forcing (mathematics),If and only if,Universe,Mathematics,Transitive relation
Journal
Volume
Issue
ISSN
17
2
0219-0613
Citations 
PageRank 
References 
3
0.46
4
Authors
1
Name
Order
Citations
PageRank
Toshimichi Usuba1144.99