An easy subexponential bound for online chain partitioning

Bosek and Krawczyk exhibited an online algorithm for partitioning an online poset of width $w$ into $w^{14\lg w}$ chains. We improve this to $w^{6.5 \lg w + 7}$ with a simpler and shorter proof by combining the work of Bosek & Krawczyk with work of Kierstead & Smith on First-Fit chain partitioning of ladder-free posets. We also provide examples illustrating the limits of our approach.Comment: 23 pages, 11 figure

On the Duality of Semiantichains and Unichain Coverings

We study a min-max relation conjectured by Saks and West: For any two posets $P$ and $Q$ the size of a maximum semiantichain and the size of a minimum unichain covering in the product $P\times Q$ are equal. For positive we state conditions on $P$ and $Q$ that imply the min-max relation. Based on these conditions we identify some new families of posets where the conjecture holds and get easy proofs for several instances where the conjecture had been verified before. However, we also have examples showing that in general the min-max relation is false, i.e., we disprove the Saks-West conjecture.Comment: 10 pages, 3 figure

Abwehr ausländischer Staatsfonds: Aktive Industriepolitik oder "neue Schutzzäune"?

Sollte das Engagement ausländischer Investoren, insbesondere Staatsfonds, in Deutschland kontrolliert werden? Roland Koch, Ministerpräsident des Landes Hessen, warnt vor möglichen staatlich gelenkten Investoren bzw. staatlich aufgelegten Fonds, die vermehrt strategisch agieren, um die Interessen ihrer Länder in für sie interessanten Märkten durchzusetzen. Seiner Meinung nach sollte Vorsorge getroffen werden, damit es nicht zu politisch motivierten Marktbeeinflussungen komme. Denkbar sei eine Anmeldepflicht größerer Transaktionen. Rainer Brüderle, FDP-Fraktion, dagegen, sieht bei einer Genehmigungspflicht bereits den "Abschied" vom freien Handel und betont, dass gerade die Deutschen von offenen Märkten und ausländischem Kapital profitieren. Auch Gunter Schall, BDI, ist der Ansicht, dass zur Aufrechterhaltung eines funktionsfähigen Marktes kartell- und wettbewerbsrechtliche Instrumente besser geeignet sind als Investitionsbeschränkungen. Allerdings erscheinen Ausnahmen in bestimmten Fällen gerechtfertigt. Diese Auffassung vertritt auch Justus Haucap, Universität Erlangen-Nürnberg. Der beste Schutz vor politischer Einflussnahme sei der funktionierende Wettbewerb auf den Produktmärkten. Anton F. Börner, Bundesverband des deutschen Groß- und Außenhandels, fordert anstatt eines Schutzwalles gegen ausländische Investitionen Reformen zur Verbesserung des Standortes Deutschland. Das Land lebe von seinen offenen Grenzen und seiner liberalen Wirtschaftsordnung; Merkantilismus und Protektionismus "im Kleid nationaler Interessen gefährde die Wettbewerbsfähigkeit". Claus Matecki, DGB, plädiert dagegen für strikte Meldepflichten und eine Aufsichtsbehörde, die die Investitionen in strategisch relevanten Bereichen kontrollieren sollte. Den Regulierungsbedarf jedoch auf Staatsfonds zu beschränken, hält er für "ordnungspolitisch ehrenhaft, ökonomisch aber nicht stichhaltig".Direktinvestition, Auslandsinvestitionsrecht, Industriepolitik, Wettbewerb, Regulierung, Protektionismus, Deutschland

Spontaneous breathing trial and post-extubation work of breathing in morbidly obese critically ill patients

Figure S5. difference in the work of breathing expressed in J/l between each test and the post-extubation period. Dashed line represents the absence of difference between the test and the post-extubation period. (JPG 44 kb

Essays In Fiscal Policy

Fiscal policy is investigated in two settings. First, a fully identified neoclassical growth model with rich fiscal policy rules is augmented with non-Ricardian consumers and fit to post-war U.S. data using Bayesian techniques. Allowing transfer payments to directly affect the consumption choices of rule-of-thumb agents permits a new interpretation of time series evidence regarding which fiscal instruments have historically financed government debt. The economic impact of fiscal adjustments is studied for two labor supply specifications. The first specification restricts labor supply by equalizing hours worked across household types. The second relaxes this assumption, allowing for intratemporal optimization by non-Ricardian households. With respect to previous findings, capital and labor taxes are more important for debt stabilization while transfers play a smaller role. Capital taxes and transfers play a larger role in output stabilization. Second, I explore the effects of anticipated policy changes. If agents are rational, they will incorporate news about future spending changes before they are enacted. I collected Federal Reserve forecasts for the period 1965 - 2005 from online archives of FOMC meetings. I incorporate the forecasts as a measure of anticipated military spending to identify government spending shocks in a VAR. When the raw forecasts are used I find that GDP, hours, wages, and consumption all rise following a shock to the news variable. When I instead incorporate forecast errors in the VAR I find just the opposite: hours increase while wages and consumption fall after a government spending shock, as is typical with the narrative approach to identifying government spending shocks, pioneered Ramey and Shapiro (1997). Thus, the way in which the forecast data is incorporated into the VAR becomes crucially important to the results. Corroborating evidence is sought using a structural model designed to study fiscal policy

Update: COPPA is Ineffective Legislation! Next Steps for Protecting Youth Privacy Rights in the Social Networking Era

In 1998, Congress passed the Children\u27s Online Privacy Protection Act (COPPA) in response to growing concerns over the dissemination of children\u27s personal information over the Internet. Under COPPA\u27s provisions, websites are prohibited from collecting personal information from children under the age of twelve without verifiable parental consent. While in theory COPPA sought to provide parents the control over their children\u27s personal information on the Internet, its practical effect causes websites to attempt to ban children through age screening mechanisms that remain largely ineffective.Twelve years after the passage of COPPA, the landscape of the Internet is dramatically changed. Social networking websites like Facebook, with over 500 million users, provide children with vast opportunities to share their personal information online. Moreover, as COPPA only seeks to protect children under the age of twelve, many of Facebook\u27s most vulnerable demographicteenagers ages thirteen to eighteenfall outside its provisions. COPPA must be revised so that children, teenagers, and parents are provided adequate notice of the uses of personal information online (especially with respect to social networking websites) and a meaningful opportunity to consent to those practices

Update: COPPA is Ineffective Legislation! Next Steps for Protecting Youth Privacy Rights in the Social Networking Era

In 1998, Congress passed the Children\u27s Online Privacy Protection Act (COPPA) in response to growing concerns over the dissemination of children\u27s personal information over the Internet. Under COPPA\u27s provisions, websites are prohibited from collecting personal information from children under the age of twelve without verifiable parental consent. While in theory COPPA sought to provide parents the control over their children\u27s personal information on the Internet, its practical effect causes websites to attempt to ban children through age screening mechanisms that remain largely ineffective.Twelve years after the passage of COPPA, the landscape of the Internet is dramatically changed. Social networking websites like Facebook, with over 500 million users, provide children with vast opportunities to share their personal information online. Moreover, as COPPA only seeks to protect children under the age of twelve, many of Facebook\u27s most vulnerable demographicteenagers ages thirteen to eighteenfall outside its provisions. COPPA must be revised so that children, teenagers, and parents are provided adequate notice of the uses of personal information online (especially with respect to social networking websites) and a meaningful opportunity to consent to those practices

Deferred on-line bipartite matching

We present a new model for the problem of on-line matching on bipartite graphs. Suppose that one part of a graph is given, but the vertices of the other part are presented in an on-line fashion. In the classical version, each incoming vertex is either irrevocably matched to a vertex from the other part or stays unmatched forever. In our version, an algorithm is allowed to match the new vertex to a group of elements (possibly empty). Later on, the algorithm can decide to remove some vertices from the group and assign them to another (just presented) vertex, with the restriction that each element belongs to at most one group. We present an optimal (deterministic) algorithm for this problem and prove that its competitive ratio equals