Orthogonal Graph Drawing with Inflexible Edges

We consider the problem of creating plane orthogonal drawings of 4-planar graphs (planar graphs with maximum degree 4) with constraints on the number of bends per edge. More precisely, we have a flexibility function assigning to each edge $e$ a natural number $\mathrm{flex}(e)$, its flexibility. The problem FlexDraw asks whether there exists an orthogonal drawing such that each edge $e$ has at most $\mathrm{flex}(e)$ bends. It is known that FlexDraw is NP-hard if $\mathrm{flex}(e) = 0$ for every edge $e$. On the other hand, FlexDraw can be solved efficiently if $\mathrm{flex}(e) \ge 1$ and is trivial if $\mathrm{flex}(e) \ge 2$ for every edge $e$. To close the gap between the NP-hardness for $\mathrm{flex}(e) = 0$ and the efficient algorithm for $\mathrm{flex}(e) \ge 1$, we investigate the computational complexity of FlexDraw in case only few edges are inflexible (i.e., have flexibility~$0$). We show that for any $\varepsilon > 0$ FlexDraw is NP-complete for instances with $O(n^\varepsilon)$ inflexible edges with pairwise distance $\Omega(n^{1-\varepsilon})$ (including the case where they induce a matching). On the other hand, we give an FPT-algorithm with running time $O(2^k\cdot n \cdot T_{\mathrm{flow}}(n))$, where $T_{\mathrm{flow}}(n)$ is the time necessary to compute a maximum flow in a planar flow network with multiple sources and sinks, and $k$ is the number of inflexible edges having at least one endpoint of degree 4.Comment: 23 pages, 5 figure

Toward an Understanding of the BDM: Predictive Validity, Gambling Effects, and Risk Attitude

Pricing research suggests incentive-compatible evaluations when consumers’ situation-specific WTP is to be elicited. Especially, the lottery-based Becker-DeGroot-Marschak-mechanism (BDM) is recommended, as it seems to outperform other elicitation methods. In this study, the BDM was used to measure subjects’ WTP for eight shopping goods in binding purchase settings. In accordance with previous studies, the validity of elicited WTP measures was checked within subjects with respect to indicators of face and criterion validity (such as interest in buying, preference ratings, and compliance rates). In addition, this study observed real purchases of a separate validation sample measured under identical circumstances, thus assessing the predictive validity of WTPs elicited with the BDM. As a result, the BDM-based WTPs reveal a sufficient degree of internal face and criterion validity. However, the external validity in terms of predictive validity between WTP-based prediction and purchases of the validation sample seems limited. Specifically, this study found a substantial overestimation of WTP, and thus in the corresponding purchase rates in the BDM. Hence, a potential bias is indicated. However, contrary to the suggestions of earlier research, individual risk attitude or loss aversion, hence a potential gambling effect, seems not to bias BDM results or the decision whether to buy or not

Entrepreneurial Human Capital, Complementary Assets, and Takeover Probability

Gaining access to technologies, competencies, and knowledge is observed as one of the major motives for corporate mergers and acquisitions. In this paper we show that a knowledge-based firm’s probability of being a takeover target is influenced by whether relevant specific human capital aimed for in acquisitions is directly accumulated within a specific firm or is bound to its founder or manager owner. We analyze the incentive effects of different arrangements of ownership in a firm’s assets in the spirit of the Grossman-Hart-Moore incomplete contracts theory of the firm. This approach highlights the organizational significance of ownership of complementary assets. In a small theoretical model we assume that the entrepreneur’s specific human capital, as measured by the patents they own, and the physical assets of their firm are productive only when used together. Our results show that it is not worthwhile for an acquirer to purchase the alienable assets of this firm due to weakened incentives for the initial owner. Regression analysis using a hand collected dataset of all German IPOs in the period from 1997 to 2006 subsequently provides empirical support for this prediction. This paper adds to previous research in that it puts empirical evidence to the Grossman-Hart-Moore framework of incomplete contracts or property rights respectively. Secondly, we show that relevant specific human capital that is accumulated by a firm’s founder or manager owner significantly decreases that firm’s probability of being a takeover target.ownership structure, property rights, mergers & acquisitions

Competitiveness – A Comparison of China and Mexico

Latin American countries have lost competitiveness in world markets in comparison to China over the last two decades. The main purpose of this study is to examine the causes of this development. To this end an augmented Ricardian model is estimated using panel data. The explanatory variables considered are productivity, unit labor costs, unit values, trade costs, price levels (in PPP), and real exchange rates in relative terms. Due to data restrictions, China’s relative exports (to the US, Argentina, Japan, Korea, UK, Germany, and Spain) will be compared to Mexico’s exports for a number of sectors over a period of eleven years. Panel and pooled estimation techniques (SUR-estimation, panel Feasible Generalized Least Squares (panel/pooled FGLS)) will be utilized to better control for country-specific effects (differences between American, Argentinian, Japanese, Korean, German, British, and Spanish markets), cross-section specific (sector-specific) effects, and correlation over time.Ricardian model of trade, panel data models, panel Feasible Generalized Least Squares, Seemingly Unrelated (SUR) estimation

The influence of time and money on product evaluations: A neurophysiological analysis

"Time is money" is how a common saying goes, reflecting a widespread assumption in many people\u27s everyday life. It seems that money and time are very similar concepts which might even be exchangeable all together. However, the neurophysiological processes underlying the activation of time or money are not yet completely understood. In order to understand in how far and in which dimensions the concept of time versus the concept of money effects human behavior we enquired the neural differences of the time versus money effect. This paper broadens the understanding of both concepts and investigates the posited distinct mindsets of time and money using functional magnetic resonance imaging (fMRI) technology. A sample of 44 righthanded adults has been analyzed. Our data supports the idea of the existence of two distinct mindsets for time and money. However, contrasting both conditions in one general linear model only a few significant differences have been found. The insula seems to be a crucial locus for the neural difference of both mindsets. Higher insula activation in the time condition suggests stronger urge for the product primed with time

Modeling the dynamics of Spain\'s Relative Export Strength

In this paper we assess the current relevance of Ricardian theory. Relative prices, labor costs, and productivity are evaluated as determinants of a country’s international competitiveness at the industry level. Working with detailed data on unit values and with industry data on productivity, we empirically implement a MacDougall-type model for Spanish and French trade to Brazil, China, Japan, and the U.S.. The period under study is 1980 to 2001 and we distinguish in our analysis between homogenous, reference-priced, and differentiated goods. Our results indicate that Ricardian theory is currently only valid for explaining trade with developing countries while other factors are of importance for developed economies. Overall price competitiveness is of importance, but for differentiated goods, factors distinct from prices seem to determine export success.

On Distributed Lags in Dynamic Panel Data Models: Evidence from Market Shares

The objective of this paper is twofold: First, the applicability of a widely used dynamic model, the autoregressive distributed lag model (ARDL), is scrutinized in a panel data setting. Second, Chile’s development of market shares in the EU market in the period of 1988 to 2002 is then analyzed in this dynamic framework, testing for the impact of price competitiveness on market shares and searching for estimation methods that deal with the problem of intertemporal and cross-section correlation of the disturbances. To estimate the coefficients of the ARDL model, Feasible Generalized Least Squares (FGLS) is utilized within the Three Stage Least Squares (3SFGLS) and the system Generalized Method of Moments (system GMM) frameworks. A computation of errors is added to highlight the usceptibility of the model to problems related to the underlying model assumptions.dynamic panel data model, autoregressive distributed lag model; pooled 3Stage Feasible Generalized Least Squares estimation, panel GMM estimation, market shares