EUDML

If is a complete theory stronger than $_{Fin}$ such that axiom of extensionality for classes + + $(\exists X) Φ_{i}$ is consistent for 1 $\leq i \leq k$ (each alone), where $Φ_{i}$ are normal formulae then we show + $(\exists X) Φ_{1} + \dots + (\exists X) Φ_{k}$ + scheme of choice is consistent. As a consequence we get: there is no proper $Δ_{1}$ -formula in + scheme of choice. Moreover the complexity of the axioms of is studied, e.gẇe show axiom of extensionality is $Π_{1}$ -formula, but not $Σ_{1}$ -formula and furthermore prolongation axiom, axioms of choice and cardinalities are $Π_{2}$ -formulae,...

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Petr Vopěnka (*16. 5. 1935)

Book reviews. Petr Vopěnka, Petr Hájek: The theory of semisets

Poznámky o linearitě zobrazení $E_{m}$ do $E_{m}$

Real classes in the ultrapower of hereditarily finite sets

Constructibility and shiftings of view

Notes on revealed classes

Addition of initial segments. I.

Metamathematics of the alternative set theory. III.

Metamathematics of the alternative set theory. II.

Der $Π$ -Prozess

Addition of initial segments. II.

Metamathematics of the alternative set theory. I.

Complexity of the axioms of the alternative set theory

Klasická logika v kontextu svých zobecnění a boj docenta Fialy proti větrným mlýnům

Indiscernibles in the alternative set theory

Shiftings of the horizon

Provability in the alternative set theory

Ultrafilters of sets

Revealments

The axiom of reflection