Multi-stack pushdown systems are a well-studied model of concurrent computationusing threads with first-order procedure calls. While, in general, reachability is unde-cidable, there are numerous restrictions on stack behaviour that lead to decidability.To model higher-order procedures calls, a generalisation of pushdown stacks called col-lapsible pushdown stacks are required. Re...

We contribute to the question about decidability of firstorder logic on configuration graphs of collapsible pushdown automata. Our first result is decidability of existential FO sentences on configuration graphs (and their ε-closures) of collapsible pushdown automata of order 3, restricted to reachable configurations. Our second result is undecidability of whole first-order logic on configurati...

Monte Carlo evidence [Evans (1991)] indicates that when speculative bubbles are collapsible, the traditional cointegration approach based on unit root tests has some serious drawbacks. We propose in this paper an alternative approach to test such bubbles. We demonstrate that the suggested test has some advantages over the traditional unit root based tests, especially for bubbles that are collap...

In this paper we give conditions on the internal wear process under which the resulting time to failure model will be of the simple collapsible form Oakes Duchesne and Lawless when the usage accumulation history is available We suppose that failure occurs when internal wear crosses a certain threshold and or a trau matic event causes the item to fail Cox and Bagdonavi cius and Nikulin We model ...

This paper presents an experimental and computational study of four deployable reflectors with collapsible edge stiffeners, to verify the differences in behavior that had been predicted in a previous theoretical study. The experimental models have different geometric configurations and are made of two different plastics. Both folding experiments and vibration tests in the fully deployed configu...

The National Institute for Occupational Safety and Health (NIOSH) at the Pittsburgh Research Laboratory (PRL) is conducting research to reduce the noise exposures of roof bolting machine operators and to prevent additional cases of Noise Induced Hearing Loss (NIHL) thru the development of engineering noise controls. This paper describes and evaluates an engineering noise control for the roof bo...

The informational odds ratio (IOR) measures the post-exposure odds divided by the pre-exposure odds (ie, information gained after knowing exposure status). A desirable property of an adjusted ratio estimate is collapsibility (ie, the combined crude ratio will not change after adjusting for a variable that is not a confounder). Adjusted traditional odds ratios (TORs) are not collapsible. In cont...

In this paper we give conditions on the internal wear process under which the resulting time-to-failure model will be of the simple collapsible form (Oakes, 1995, Duchesne and Lawless, 2000) when the usage accumulation history is available. We suppose that failure occurs when internal wear crosses a certain threshold and/or a traumatic event causes the item to fail (Cox, 1999 and Bagdonavi cius...

In general a contractible simplicial complex need not be collapsible. Moreover, there exist complexes which are collapsible but even so admit collapsing sequence where one “gets stuck”, that is can choose the collapses in such way arrives at nontrivial admits no moves. Here we examine this phenomenon case of simplex. particular, characterize all values n and d n-simplex may collapse to d-comple...

This article studies a large class of two-player perfect-information turn-based parity games on infinite graphs, namely, those generated by collapsible pushdown automata. The main motivation for studying these comes from the connections automata and higher-order recursion schemes, both models being equi-expressive generating trees. Our result is to establish decidability such provide an effecti...