Generating Property-Directed Potential Invariants By Backward Analysis

This paper addresses the issue of lemma generation in a k-induction-based formal analysis of transition systems, in the linear real/integer arithmetic fragment. A backward analysis, powered by quantifier elimination, is used to output preimages of the negation of the proof objective, viewed as unauthorized states, or gray states. Two heuristics are proposed to take advantage of this source of information. First, a thorough exploration of the possible partitionings of the gray state space discovers new relations between state variables, representing potential invariants. Second, an inexact exploration regroups and over-approximates disjoint areas of the gray state space, also to discover new relations between state variables. k-induction is used to isolate the invariants and check if they strengthen the proof objective. These heuristics can be used on the first preimage of the backward exploration, and each time a new one is output, refining the information on the gray states. In our context of critical avionics embedded systems, we show that our approach is able to outperform other academic or commercial tools on examples of interest in our application field. The method is introduced and motivated through two main examples, one of which was provided by Rockwell Collins, in a collaborative formal verification framework.Comment: In Proceedings FTSCS 2012, arXiv:1212.657

Why economics should be a modest and reasonable science

Unlike the methodological sciences such as mathematics and decision theory, which use the hypothetical-deductive method and may be fully expressed in complex mathematical models because their only truth criterion is logical consistency, the substantive sciences have as their truth criterion the correspondence to reality, adopt an empirical-deductive method, and are supposed to generalize from and often unreliable regularities and tendencies. Given this assumption, it is very difficult for economists to predict economic behavior, particularly major financial crises.

Did F. A. Hayek Embrace Popperian Falsificationism? A Critical Comment About Certain Theses of Popper, Duhem and Austrian Methodology

Hayek´s methodological outlook at the time he engaged in business cycle research was actually closer to praxeological apriorism than to Popperian falsificationism. A consideration of the Duhem thesis highlights the fact that even from a mainstream methodological perspective falsificationism is more problematic than is often realized. Even if the praxeological and mainstream lines of argumentation reject the Popperian emphasis on falsification for different reasons and from a different background, the prospects for falsificationism in economic methodology seem rather bleak.General methodology; falsificationism; Popper; Hayek; Duhem; Duhemian Argument; Testing of Theories; Meaning and Interpretation of Econometric Results; Correlation and Causality;

The Ontological Backlash: why did mainstream analytic philosophy lose interest in the philosophy of history?

This paper seeks to explain why mainstream analytic philosophy lost interest in the philosophy of history. It suggests that the reasons why the philosophy of history no longer commands the attention of mainstream analytical philosophy may be explained by the success of an ontological backlash against the linguistic turn and a view of philosophy as a form of conceptual analysis. In brief I argue that in the 1950s and 1960s the philosophy of history attracted the interest of mainstream analytical philosophers because the defence of the autonomy of historical explanation championed by the likes of Collingwood, Dray, Melden, Winch, Von Wright and others was in tune with the predominant conception of philosophy as a conceptual enterprise concerned primarily with clarifying different explanatory practices. As this conception of philosophy as an essentially conceptual enterprise became recessive, the purely methodological non-reductivism advocated by defenders of the autonomy of history was accused of ontological escapism and the discussion concerning the autonomy of psychological explanations became the province of the philosophy of mind and action

An investigation of machine learning based prediction systems

Traditionally, researchers have used either o�f-the-shelf models such as COCOMO, or developed local models using statistical techniques such as stepwise regression, to obtain software eff�ort estimates. More recently, attention has turned to a variety of machine learning methods such as artifcial neural networks (ANNs), case-based reasoning (CBR) and rule induction (RI). This paper outlines some comparative research into the use of these three machine learning methods to build software e�ort prediction systems. We briefly describe each method and then apply the techniques to a dataset of 81 software projects derived from a Canadian software house in the late 1980s. We compare the prediction systems in terms of three factors: accuracy, explanatory value and configurability. We show that ANN methods have superior accuracy and that RI methods are least accurate. However, this view is somewhat counteracted by problems with explanatory value and configurability. For example, we found that considerable eff�ort was required to configure the ANN and that this compared very unfavourably with the other techniques, particularly CBR and least squares regression (LSR). We suggest that further work be carried out, both to further explore interaction between the enduser and the prediction system, and also to facilitate configuration, particularly of ANNs

A comparative survey of integrated learning systems

This paper presents the duction framework for unifying the three basic forms of inference - deduction, abduction, and induction - by specifying the possible relationships and influences among them in the context of integrated learning. Special assumptive forms of inference are defined that extend the use of these inference methods, and the properties of these forms are explored. A comparison to a related inference-based learning frame work is made. Finally several existing integrated learning programs are examined in the perspective of the duction framework