Faster exponential-time algorithms in graphs of bounded average degree

We first show that the Traveling Salesman Problem in an n-vertex graph with average degree bounded by d can be solved in O*(2^{(1-\eps_d)n}) time and exponential space for a constant \eps_d depending only on d, where the O*-notation suppresses factors polynomial in the input size. Thus, we generalize the recent results of Bjorklund et al. [TALG 2012] on graphs of bounded degree. Then, we move to the problem of counting perfect matchings in a graph. We first present a simple algorithm for counting perfect matchings in an n-vertex graph in O*(2^{n/2}) time and polynomial space; our algorithm matches the complexity bounds of the algorithm of Bjorklund [SODA 2012], but relies on inclusion-exclusion principle instead of algebraic transformations. Building upon this result, we show that the number of perfect matchings in an n-vertex graph with average degree bounded by d can be computed in O*(2^{(1-\eps_{2d})n/2}) time and exponential space, where \eps_{2d} is the constant obtained by us for the Traveling Salesman Problem in graphs of average degree at most 2d. Moreover we obtain a simple algorithm that counts the number of perfect matchings in an n-vertex bipartite graph of average degree at most d in O*(2^{(1-1/(3.55d))n/2}) time, improving and simplifying the recent result of Izumi and Wadayama [FOCS 2012].Comment: 10 page

Families with infants: a general approach to solve hard partition problems

We introduce a general approach for solving partition problems where the goal is to represent a given set as a union (either disjoint or not) of subsets satisfying certain properties. Many NP-hard problems can be naturally stated as such partition problems. We show that if one can find a large enough system of so-called families with infants for a given problem, then this problem can be solved faster than by a straightforward algorithm. We use this approach to improve known bounds for several NP-hard problems as well as to simplify the proofs of several known results. For the chromatic number problem we present an algorithm with $O^*((2-\varepsilon(d))^n)$ time and exponential space for graphs of average degree $d$. This improves the algorithm by Bj\"{o}rklund et al. [Theory Comput. Syst. 2010] that works for graphs of bounded maximum (as opposed to average) degree and closes an open problem stated by Cygan and Pilipczuk [ICALP 2013]. For the traveling salesman problem we give an algorithm working in $O^*((2-\varepsilon(d))^n)$ time and polynomial space for graphs of average degree $d$. The previously known results of this kind is a polyspace algorithm by Bj\"{o}rklund et al. [ICALP 2008] for graphs of bounded maximum degree and an exponential space algorithm for bounded average degree by Cygan and Pilipczuk [ICALP 2013]. For counting perfect matching in graphs of average degree~$d$ we present an algorithm with running time $O^*((2-\varepsilon(d))^{n/2})$ and polynomial space. Recent algorithms of this kind due to Cygan, Pilipczuk [ICALP 2013] and Izumi, Wadayama [FOCS 2012] (for bipartite graphs only) use exponential space.Comment: 18 pages, a revised version of this paper is available at http://arxiv.org/abs/1410.220

Enhancing creative knowledge-work: challenges and points of leverage

Purpose– The purpose of this paper is to explore critical success factors in knowledge‐intensive creative project work, using product development as an example field. Design/methodology/approach– Critical‐incident based in‐depth interviews of 11 product development experts (chosen based on their recommendations and length of experience) were carried out. The results were categorized into thematic classes of critical factors. Findings– Most challenges are embedded in the context of the product development projects. Collaboration and cognitive‐motivational factors such as trust, attitude, and intrinsic motivation‐related issues formed the most common classes of discovered critical factors behind product development project success, along with the mediating categories of goal and autonomy‐related factors. Furthermore, product development specific skills or knowledge accounted only for a small minority of the identified factors. Practical implications– The most pressing learning objective becomes not updating product development knowledge, but that of increasing motivation, initiative, trust, and collaboration. As the discovered challenges are embedded in the context of work, addressing them ultimately requires project managers to master some of the personnel development aspects traditionally left for human resources management. Training efforts need to be tailored to the project context if they are to have a lasting impact on behavior. Originality/value– In addition to providing further support for the importance of climate factors, this paper suggests that special attention should be directed towards goal setting and autonomy, as they play a significant role in many of the climate and cognitive‐motivational constructs increasing creativity.Peer reviewe

Initial mental representations of design problems: Differences between experts and novices

Defining and structuring wicked design problems has a major influence on subsequent problem solving, and demands a considerable level of skill. Previous research on mental representations in design is scarce, and has been largely based on students or individual experts. This study explored the differences in the initial mental representations of real-life product development problems between advanced product development engineering students and recommended, professional experts. Expert mental representations were found to demonstrate superior extent, depth and level of detail, accommodating more interconnections and being more geared toward action. The results indicate that targeting relevancy perceptions to locate interconnections and promote proactivity can be a key factor in developing product development education to better match the requirements faced by professionals.Peer reviewe

Adapting to the changing needs of managing innovative projects

Purpose – The purpose of this paper is to explore the changes in managerial activities and challengesat different phases of innovative projects. Design/methodology/approach – Six NPD project managers were interviewed in three differentproject phases in a qualitative, longitudinal design. The resulting 18 semi-structured face-to-faceinterviews were content analyzed and categorized according to thematic similarity. Findings – Altogether 19 categories describing managerial concerns in managing innovative projectswere recognized. Task-oriented, rather than people-oriented, approaches were dominant throughoutthe projects, although the reported concerns clearly varied at each phase. The early development phaseemerged as a transition point, where managers had to transform their roles, reported activitiesdecreased, and reported challenges increased. Research limitations/implications – Although based on a small number of participants in a singlesetting, the results highlight the need for longitudinal studies and differentiating between the variousphases of the innovation process, as there was great variance in the concerns of each phase.Furthermore, domain expertise seemed to have a large impact on how the managers reformulated theirrole in transitioning from the front-end to the development phases. Practical implications – The present study emphasizes the need to support managers intransitioning between different innovation phases and to recognize the need to adjust managerial roles.Further, it seemed crucial to establish the practices supporting successful teamwork in the front-endphase before the first phase transition. Originality/value – The study is a rare example of a longitudinal research design examining theimplications and transition between different phases of the innovation process within the sameprojects for project managers.Peer reviewe

The central role of exploration in designing business concepts and strategy

Design thinking is described as a combination of thinking and acting that leads to new solution possibilities for design problems. Though traditionally linked to the design of objects and services, it can be applied to organizational processes as well. This paper examines design thinking in developing a new business, focusing on the business concept and strategy formation in the start-up phase of the company. How and what elements of design thinking are manifested in the process of designing a business concept and forming a strategy? What is the importance of these elements in this process? The results reveal the experimental and iterative nature of developing the business concept and strategy. In addition, these organizational processes were strongly influenced by the product offering, stakeholders, and environment that the company operated in. While the results highlighted the importance of emergence, they also illustrated a need for structure and planning, thus reminding of the need of balancing between the two. Overall, the results suggest that many of the fundamental elements of design thinking are found in the development process of a company.Peer reviewe

Simulation Subsumption or Déjà vu on the Web

Simulation unification is a special kind of unification adapted to retrieving semi-structured data on the Web. This article introduces simulation subsumption, or containment, that is, query subsumption under simulation unification. Simulation subsumption is crucial in general for query optimization, in particular for optimizing pattern-based search engines, and for the termination of recursive rule-based web languages such as the XML and RDF query language Xcerpt. This paper first motivates and formalizes simulation subsumption. Then, it establishes decidability of simulation subsumption for advanced query patterns featuring descendant constructs, regular expressions, negative subterms (or subterm exclusions), and multiple variable occurrences. Finally, we show that subsumption between two query terms can be decided in O(n!n) where n is the sum of the sizes of both query terms

Animal Models of Parkinson's Disease: Are They Useful or Not?

The use of animal models in Parkinson's disease research has been controversial in terms of how well they relate to the clinical condition and thus their utility for translating therapies from the lab to the clinic. In this article, two researchers debate this issue with Roger Barker taking the view that such models are not useful and may even be misleading, while Anders Björklund defends their use and highlights their value in better understanding and treating this condition.This is just a discussion piece, so no funding acknowledged

Generating resources through co-evolution of entrepreneurs and ecosystems

Purpose – The emerging perspectives of entrepreneurial ecosystems, bricolage and effectuationhighlight the interaction between the entrepreneur and the surrounding community, and its potentialfor creative resource acquisition and utilization. However, empirical work on how this process actuallyunfolds remains scarce. This paper aims to study the interaction between the opportunity constructionprocess and the development of resources in the surrounding ecosystem. Design/methodology/approach – This paper is a qualitative analysis of the extreme case of AaltoEntrepreneurship Society (Aaltoes), a newly founded organization successfully promotingentrepreneurship within a university merger with virtually no resources, based on interviews of six keycontributors and four stakeholder organisations. Findings – The opportunity construction process both supported and was supported by two keyresource generating mechanisms. Formulating and opportunistically reformulating the agenda forincreasing potential synergy laid the groundwork for mutual benefit. Proactive concretization enhancedboth initial resource allocation and sustaining input to the process through offering tangible instancesof specific opportunities and feedback. Research limitations/implications – Although based on a single case study in a university setting,proactive concretization emerges as a promising direction for further investigations of the benefits anddynamics of entrepreneur– ecosystem interaction in the opportunity construction process. Practical implications – Intentionally creating beneficial entrepreneur– ecosystem interaction andteaching proactive concretization becomes a key goal for educators of entrepreneurship. Originality/value – The paper extends an understanding of creative resource generation and utilizationin the opportunity construction process. The role of proactive concretization was emphasized in theinteraction of the entrepreneur and the ecosystem, creating virtuous spirals of entrepreneurial activity.Peer reviewe

Spotting Trees with Few Leaves

We show two results related to the Hamiltonicity and $k$-Path algorithms in undirected graphs by Bj\"orklund [FOCS'10], and Bj\"orklund et al., [arXiv'10]. First, we demonstrate that the technique used can be generalized to finding some $k$-vertex tree with $l$ leaves in an $n$-vertex undirected graph in $O^*(1.657^k2^{l/2})$ time. It can be applied as a subroutine to solve the $k$-Internal Spanning Tree ($k$-IST) problem in $O^*(\min(3.455^k, 1.946^n))$ time using polynomial space, improving upon previous algorithms for this problem. In particular, for the first time we break the natural barrier of $O^*(2^n)$. Second, we show that the iterated random bipartition employed by the algorithm can be improved whenever the host graph admits a vertex coloring with few colors; it can be an ordinary proper vertex coloring, a fractional vertex coloring, or a vector coloring. In effect, we show improved bounds for $k$-Path and Hamiltonicity in any graph of maximum degree $\Delta=4,\ldots,12$ or with vector chromatic number at most 8