Morita Equivalence of C^*-Crossed Products by Inverse Semigroup Actions and Partial Actions

Morita equivalence of twisted inverse semigroup actions and discrete twisted partial actions are introduced. Morita equivalent actions have Morita equivalent crossed products

C*-actions of r-discrete groupoids and inverse semigroups

Groupoid actions on C*-bundles and inverse semigroup actions on C*-algebras are closely related when the groupoid is r-discrete.Comment: LaTeX-2e, 18 pages, uses pb-diagram.st

Biased Weak Polyform Achievement Games

In a biased weak $(a,b)$ polyform achievement game, the maker and the breaker alternately mark $a,b$ previously unmarked cells on an infinite board, respectively. The maker's goal is to mark a set of cells congruent to a polyform. The breaker tries to prevent the maker from achieving this goal. A winning maker strategy for the $(a,b)$ game can be built from winning strategies for games involving fewer marks for the maker and the breaker. A new type of breaker strategy called the priority strategy is introduced. The winners are determined for all $(a,b)$ pairs for polyiamonds and polyominoes up to size four

Impartial achievement and avoidance games for generating finite groups

We study two impartial games introduced by Anderson and Harary and further developed by Barnes. Both games are played by two players who alternately select previously unselected elements of a finite group. The first player who builds a generating set from the jointly selected elements wins the first game. The first player who cannot select an element without building a generating set loses the second game. After the development of some general results, we determine the nim-numbers of these games for abelian and dihedral groups. We also present some conjectures based on computer calculations. Our main computational and theoretical tool is the structure diagram of a game, which is a type of identification digraph of the game digraph that is compatible with the nim-numbers of the positions. Structure diagrams also provide simple yet intuitive visualizations of these games that capture the complexity of the positions.Comment: 28 pages, 44 figures. Revised in response to comments from refere

The Effects of Human Resource Management on Workers' Wages and Firm Productivity

We analyze whether the effects of human resource practices on workers’ wages and firm productivity are similar or different. We find that firms’ wage policies overestimate the relevance of sector-specific skills and underestimate the productivity enhancing effect of computer skills. Moreover, only the firm benefits from performance related pay, whereas only the workers benefit from performance evaluation interviews. Finally, our estimation results show that in small firms a more advanced HRM system may not result in a convergence of interests between workers and the firm.education, training and the labour market;