4 papers
Arrow-chasing in Pascal's triangle -- Visual proofs for summation formulas involving binomial coefficients
Regula Krapf
This article demonstrates, using numerous examples of varying complexity, how one can visually prove summation formulas involving binomial coefficients by exclusively using the rec…
Sufficient conditions for the forcing theorem, and turning proper classes into sets
Peter Holy, Regula Krapf, Philipp Schlicht
We present three natural combinatorial properties for class forcing notions, which imply the forcing theorem to hold. We then show that all known sufficent conditions for the forci…
Characterizations of pretameness and the Ord-cc
Peter Holy, Regula Krapf, Philipp Schlicht
It is well known that pretameness implies the forcing theorem, and that pretameness is characterized by the preservation of the axioms of , that is wit…
Class forcing, the forcing theorem and Boolean completions
Peter Holy, Regula Krapf, Philipp Lücke +2
The forcing theorem is the most fundamental result about set forcing, stating that the forcing relation for any set forcing is definable and that the truth lemma holds, that is eve…