131 research outputs found
Some Intuition behind Large Cardinal Axioms, Their Characterization, and Related Results
We aim to explain the intuition behind several large cardinal axioms, give characterization theorems for these axioms, and then discuss a few of their properties. As a capstone, we hope to introduce a new large cardinal notion and give a similar characterization theorem of this new notion. Our new notion of near strong compactness was inspired by the similar notion of near supercompactness, due to Jason Schanker
Subcompact cardinals, squares, and stationary reflection
We generalise Jensen's result on the incompatibility of subcompactness with
square. We show that alpha^+-subcompactness of some cardinal less than or equal
to alpha precludes square_alpha, but also that square may be forced to hold
everywhere where this obstruction is not present. The forcing also preserves
other strong large cardinals. Similar results are also given for stationary
reflection, with a corresponding strengthening of the large cardinal assumption
involved. Finally, we refine the analysis by considering Schimmerling's
hierarchy of weak squares, showing which cases are precluded by
alpha^+-subcompactness, and again we demonstrate the optimality of our results
by forcing the strongest possible squares under these restrictions to hold.Comment: 18 pages. Corrections and improvements from referee's report mad
Laver and set theory
In this commemorative article, the work of Richard Laver is surveyed in its full range and extent.Accepted manuscrip
Dense ideals and cardinal arithmetic
From large cardinals we show the consistency of normal, fine,
-complete -dense ideals on for
successor . We explore the interplay between dense ideals, cardinal
arithmetic, and squares, answering some open questions of Foreman
Inner models with large cardinal features usually obtained by forcing
We construct a variety of inner models exhibiting features usually obtained
by forcing over universes with large cardinals. For example, if there is a
supercompact cardinal, then there is an inner model with a Laver indestructible
supercompact cardinal. If there is a supercompact cardinal, then there is an
inner model with a supercompact cardinal \kappa for which 2^\kappa=\kappa^+,
another for which 2^\kappa=\kappa^++ and another in which the least strongly
compact cardinal is supercompact. If there is a strongly compact cardinal, then
there is an inner model with a strongly compact cardinal, for which the
measurable cardinals are bounded below it and another inner model W with a
strongly compact cardinal \kappa, such that H_{\kappa^+}^V\subseteq HOD^W.
Similar facts hold for supercompact, measurable and strongly Ramsey cardinals.
If a cardinal is supercompact up to a weakly iterable cardinal, then there is
an inner model of the Proper Forcing Axiom and another inner model with a
supercompact cardinal in which GCH+V=HOD holds. Under the same hypothesis,
there is an inner model with level by level equivalence between strong
compactness and supercompactness, and indeed, another in which there is level
by level inequivalence between strong compactness and supercompactness. If a
cardinal is strongly compact up to a weakly iterable cardinal, then there is an
inner model in which the least measurable cardinal is strongly compact. If
there is a weakly iterable limit \delta of <\delta-supercompact cardinals, then
there is an inner model with a proper class of Laver-indestructible
supercompact cardinals. We describe three general proof methods, which can be
used to prove many similar results
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