Professor Willem Willems 1950–2014

Willem Blok and Modal Logic

We present our personal view on W.J. Blok’s contribution to modal logic.

Willem A . de Graaf

Arno Van Den Essen , Roel Willems And

In this paper we prove four cases of the vanishing conjecture of differential operators with constant coefficients and also a conjecture on the Laurent polynomials with no holomorphic parts, which were proposed in [Zh3] by the third named author. We also give two examples to show that the generalizations of both the vanishing conjecture and the Duistermaat-van der Kallen theorem [DK] to Laurent...

The Dialectic of Teleologyl Willem

Teleology is a central concept in Hegel's philosophy, but, as is too common in his writing, exactly what he understands under that concept, what role within his philosophy it plays, and how he defends his position remain obscure. Hegel did not come to his position on teleology in a vacuum; it was a topic of major concern to his predecessors as well. Then as now, debate focused both on the quest...

2 WILLEM VISSER AND HOWARD BARRINGEREarly

The use of an Ordered Binary Decision Diagram (OBDD) to store all visited states during on-they model checking (or reachability analysis) is investigated. To improve the time and space eeciency a state compression technique is introduced. This compression technique is safe, in the sense that no two unique states will have the same compressed representation. A number of examples are used to eval...