51 research outputs found

    Analytical Guide and updates for "Cardinal Arithmetic"

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    Part A: A revised version of the guide in "Cardinal Arithmetic" ([Sh:g]), with corrections and expanded to include later works. Part B: Corrections to [Sh:g]. Part C: Contains some revised proof and improved theorems. Part D: Contains a list of relevant references

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    On what I do not understand (and have something to say): Part I

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    This is a non-standard paper, containing some problems in set theory I have in various degrees been interested in. Sometimes with a discussion on what I have to say; sometimes, of what makes them interesting to me, sometimes the problems are presented with a discussion of how I have tried to solve them, and sometimes with failed tries, anecdote and opinion. So the discussion is quite personal, in other words, egocentric and somewhat accidental. As we discuss many problems, history and side references are erratic, usually kept at a minimum (``see ... '' means: see the references there and possibly the paper itself). The base were lectures in Rutgers Fall'97 and reflect my knowledge then. The other half, concentrating on model theory, will subsequently appear

    Middle Diamond

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    Under some cardinal arithmetic assumptions, we prove that many stationary subsets of lambda of a right cofinality has the ``middle diamond''. In particular, for many regular kappa for every large enough regular lambda we have the middle diamond on {delta<lambda: cf(delta)= kappa}. This is a strong negation of uniformization

    Non existence of universals for classes like reduced torsion free abelian groups under non neccessarily pure embeddings

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    We consider a class K of structures e.g. trees with omega +1 levels, metric spaces and mainly, classes of Abelian groups like the one mentioned in the title and the class of reduced separable (Abelian) p-groups. We say M in K is universal for K if any member N of K of cardinality not bigger than the cardinality of M can be embedded into M . This is a natural, often raised, problem. We try to draw consequences of cardinal arithmetic to non--existence of universal members for such natural classes
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