Extended Initiality for Typed Abstract Syntax

Initial Semantics aims at interpreting the syntax associated to a signature as the initial object of some category of 'models', yielding induction and recursion principles for abstract syntax. Zsid\'o proves an initiality result for simply-typed syntax: given a signature S, the abstract syntax associated to S constitutes the initial object in a category of models of S in monads. However, the iteration principle her theorem provides only accounts for translations between two languages over a fixed set of object types. We generalize Zsid\'o's notion of model such that object types may vary, yielding a larger category, while preserving initiality of the syntax therein. Thus we obtain an extended initiality theorem for typed abstract syntax, in which translations between terms over different types can be specified via the associated category-theoretic iteration operator as an initial morphism. Our definitions ensure that translations specified via initiality are type-safe, i.e. compatible with the typing in the source and target language in the obvious sense. Our main example is given via the propositions-as-types paradigm: we specify propositions and inference rules of classical and intuitionistic propositional logics through their respective typed signatures. Afterwards we use the category--theoretic iteration operator to specify a double negation translation from the former to the latter. A second example is given by the signature of PCF. For this particular case, we formalize the theorem in the proof assistant Coq. Afterwards we specify, via the category-theoretic iteration operator, translations from PCF to the untyped lambda calculus

Topics in entrepreneurship and family business management

Chapter 1: Nepotism - CEO Succession, Ownership and Enterprise Performance By JAN-PHILIPP AHRENS, SANDRA GOTTSCHALK AND MICHAEL WOYWODE We consider the effects of CEO successions on enterprise performance in medium-sized enterprises with strong ownership concentration (family firms). By evaluating an unique data set we show that firms which install relatives or heirs as CEO successors perform worse as compared to firms which install external CEO successors. Furthermore we identify the driving forces behind this inferior performance as lower human capital and a lower propensity to implement organizational changes, which is presumably caused by limited selectivity of CEO succession contests due to concentrated ownership structures. Interestingly, no performance gap is observable for well-chosen high human capital family successors. (JEL: E32, G30, J24, L25, M51) Keywords: CEO succession, ownership structure, nepotism, agency costs, firm performance. Chapter 2: Inside CEO Successions in Family Firms: Should Predecessors Stay Active or Cultivate Roses? By JAN-PHILIPP AHRENS, MICHAEL WOYWODE, AND JAN ZYBURA Employing an unique data set on CEO successions, we analyze the circumstances under which departing CEOs stay active within their enterprise subsequent to a CEO succession and highlight enterprise performance implications. We find that the likelihood of predecessor activity is increased by family succession, nepotism and tacit knowledge, but reduced by the successor’s human capital, successor’s ownership and corporate age. The performance impact of prolonged predecessor activity is positive for successors with low human capital, but turns negative with increased successor human capital, while this negative impact is amplified by the degree of influence of the preceding CEO. (JEL: G32, G34, L25, M1, M51) Keywords: CEO succession, firm performance, family owned business, human capital, leadership transition Chapter 3: Gender Preferences in CEO Successions in Family Firms: Family Characteristics and Human Capital of the Successor By JAN-PHILIPP AHRENS, ANDREAS LANDMANN, AND MICHAEL WOYWODE We investigate labor market constraints in CEO succession contests devising an unique data set on CEO successions in enterprises with concentrated ownership and control. We find that a preference for male family heirs limits labor market selectivity: Family successions are significantly more likely to occur when a son is among the predecessor’s children as compared to daughters. Sons among the children increase the likelihood of nepotistic successions, while in turn female family successors are equipped with higher human capital due to tougher selectivity criteria. Furthermore, the regional industry supply of CEO resources influences the observed human capital of installed successors. (JEL: G30, J13, J24, L26, M51) Keywords: CEO succession, family firms, family characteristics, human capital, promotion decisions. Chapter 4: Restructuring, Human Capital, and Enterprise Performance in CEO Successions in Family Firms By JAN-PHILIPP AHRENS AND MICHAEL WOYWODE Devising an unique data set we analyze managerial actions and their performance impact during CEO successions in family firms. We find that corporate change unleashes additional performance due to accumulated improvement potentials from the pre-succession period. High human capital successors implement more changes and perform significantly better when compared to low human capital successors. Furthermore, the amount of observed changes is subject to the economic contingency and is highest in CEO successions in turnaround situations. In particular reviews of the supplier relations, the product portfolio, and the compensation scheme were found to significantly enhance performance. (JEL: G30, G34, L25, M10, M51) Keywords: CEO succession, family firms, organizational restructuring, turnaround management, human capital, firm performance. Chapter 5: Entrepreneurship under Imperfect Institutions By JAN-PHILIPP AHRENS AND MICHAEL WOYWODE We consider the effects of imperfect institutions on entrepreneurial activity. Employing a microeconomic model, we argue abnormal uncertainty and transactions costs reduce profitability and volume of entrepreneurial activity while companies complying with good practices enjoy rewards in the optimal contracts. However, applied to an international context, counterintuitive niche cases where imperfect institutions enhance the wealth of nations occur, mirroring seemingly contrary findings in the development literature. Policies and business strategies to escape imperfect institutions are discussed, casting light on medieval merchant guilds or township and village enterprises and arguing for a holistic approach when introducing policies for institutional change. (JEL: D02, D21, D82, D86, F23, L26, O34, O43, R00) Keywords: Entrepreneurship, Principal-Agent Model, Institutions, Institutional Change, Development Economic

Optisch-parametrische Verstärkersysteme bei hohen Pulswiederholraten

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Interstate 80 East

This book was completed for Jan Baker\u27s artists\u27 book class.https://digitalcommons.risd.edu/specialcollections_bookmark_stories/1000/thumbnail.jp

Tunable sub-20 fs pulses from a 500 kHz OPCPA with 15 W average power based on an all-ytterbium laser

An optical parametric chirped pulse amplifier fully based on Yb lasers at 500 kHz is described. Passive optical-synchronization is achieved between a fiber laser-pumped white-light and a 515 nm pump produced with a 200 W picosecond Yb:YAG InnoSlab amplifier. An output power up to 19.7 W with long-term stability of 0.3% is demonstrated for wavelength tunable pulses between 680 nm and 900 nm and spectral stability of 0.2%; 16.5 W can be achieved with a bandwidth supporting 5.4 fs pulses. We demonstrate compression of 30 microjoule pulses to sub-20 fs duration with a prism compressor, suitable for high harmonic generation.Comment: 4 pages, 4 figure