Local Maxima of Quadratic Boolean Functions

How many strict local maxima can a real quadratic function on $\{0,1\}^n$ have? Holzman conjectured a maximum of $n \choose \lfloor n/2 \rfloor$. The aim of this paper is to prove this conjecture. Our approach is via a generalization of Sperner's theorem that may be of independent interest.Comment: 6 pages, 1 figur

An assessment of post-plague reintroduced native white-clawed crayfish, a Ustropotamobius pallipes, in the Sherston Avon and Tetbury Avon, Wiltshire

This article reports on the success of reintroducing native crayfish (Austropotamobius pallipes) in the Sherston and Tetbury Avon, following extinction of the population from crayfish plague. The authors describe and review the survey methods that were used and identify a survey technique that was found to be the most rapid and robust for monitoring crayfish populations. Such a survey technique could be adopted as a standard method

The current distribution of signal and native crayfish in the Broadmead Brook, Wiltshire

Signal crayfish (Pacifastacus leniusculus) have existed in the upper reaches of Broadmead Brook in Wiltshire since 200 individuals were introduced at West Kington in 1981. The population has expanded upstream and downstream since this introduction, however, giving rise to concerns that it may potentially threaten the native crayfish population further downstream. Signal crayfish can act as a vector of crayfish plague - a disease caused by the fungus Aphanomyces astaci Schikora which results in almost complete mortality to the native, white-clawed crayfish Austropotamobius pallipes. The native crayfish in Broadmead Brook have not yet succumbed to crayfish plague and are currently free of the disease. However, as signal crayfish appear to out-compete the native species, the native population could still be under threat. In this article, we highlight the findings of previous crayfish surveys on Broadmead Brook and describe work undertaken in summer 2001 to map the current distribution of native and signal crayfish. Finally, options for controlling the spread of signal crayfish are discussed

A Human Information Behavior Approach to a Philosophy of Information

This paper outlines the relation between philosophy of information (PI) and human information behavior (HIB). In this paper, we first briefly outline the basic constructs and approaches of PI and HIB. We argue that a strong relation exists between PI and HIB, as both are exploring the concept of information and premise information as a fundamental concept basic to human existence. We then exemplify that a heuristic approach to PI integrates the HIB view of information as a cognitive human- initiated process by presenting a specific cognitive architecture for information initiation based on modular notion from HIB/evolutionary psychology and the vacuum mechanism from PI.published or submitted for publicatio

A study of search intermediary working notes: implications for IR system design

This paper reports findings from an exploratory study investigating working notes created during encoding and external storage (EES) processes, by human search intermediates using a Boolean information retrieval (JR) system. EES processes have been an important area of research in educational contexts where students create and use notes to facilitate learning. In the context of interactive IR, encoding can be conceptualized as the process of creating working notes to help in the understanding and translating a user's information problem into a search strategy suitable for use with an IR system. External storage is the process of using working notes to facilitate interaction with IR systems. Analysis of 221 sets of working notes created by human search intermediaries revealed extensive use of EES processes and the creation of working notes of textual, numerical and graphical entities. Nearly 70% of recorded working notes were textual/numerical entities, nearly 30% were graphical entities and 0.73% were indiscernible. Segmentation devices were also used in 48% of the working notes. The creation of working notes during EES processes was a fundamental element within the mediated, interactive IR process. Implications for the design of IR interfaces to support users' EES processes and further research is discussed