Reinvigorating Horizontal Merger Enforcement

The past forty years have witnessed a remarkable transformation in horizontal merger enforcement in the United States. With no change in the underlying statute, the Clayton Act, the weight given to market concentration by the federal courts and by the federal antitrust agencies has declined dramatically. Instead, increasing weight has been given to three arguments often made by merging firms in their defense: entry, expansion and efficiencies. We document this shift and provide examples where courts have approved highly concentrating mergers based on limited evidence of entry and expansion. We show using merger enforcement data and a survey we conducted of merger practitioners that the decline in antitrust enforcement is ongoing, especially at the current Justice Department. We then argue in favor of reinvigorating horizontal merger enforcement by partially restoring the structural presumption and by requiring strong evidence to overcome the government's prima facie case. We propose several routes by which the government can establish its prima facie case, distinguishing between cases involving coordinated vs. unilateral anti-competitive effects.

Hymenoptera Two New Bees of the Genus Ceratina

Female Length 11 mm. Head mostly except the black vertex, thorax except the black entire median portion of the menosotum, brilliant green, with a slight brassy tinge. Abdomen deep shining purple. Antennae and legs piceous, the latter, together with the venter, covered with rather long and thick ferrugineous pubescence. Wings uniformly pale smoky and iridescent, the veins ,lark, the stigma translucent. First submarginal cell about twice the length of second, the first abscissa of radius equalling third

Hymenoptera the Bee Genus Pasiphae in North America

While in Central America I collected a number of species of Prosopis (descriptions to appear soon) which were typical representatives of that genus in every way. Scattered through this collection were a number of bees, very Prosopis-like, but possessing a truncated and appendiculated marginal cell and otherwise corresponding to Ashmead \u27s description of the genus Pasiphae, previously known only from the southern Andean region. In Trans. Am. Ent. Soc. XXIX, p. 186, Cockerell says Mr. Vachal remarks that this has a distinct tibial pollen brush,. and cannot go with the Prosopidae. It appears to be a Colletid with only two submarginal cells.\u27\u27 The Prosopidae arc usually described almost without reservation, as \u27\u27non-pubescent\u27\u27, a statement that should be considerably modified. It is true that the pubescence is reduced-thin and fine, but distinctly present over most of the body in all of the American species I have seen. What the naked eye or the simple lens does not show in this case, the compound microscope will prove a clearly distinct feature. If the hind tibiae of any Prosopis are carefully examined, they will be found usually thickly covered with pubescence. In these Central American bees which I am calling Pasiphae, this pubescence is more pronounced than I have found it in any Prosopis. and while it might possibly be called a \u27\u27distinct pollen brush\u27\u27, still I cannot sec it as especially similar to any Colletid and believe that the status and relationships of the genus are as stated by Ashmead. The genus Stilpnosoma, which is placed in the Prospidae, is still more pubescent, the hind tibiae very thickly so. In S. turneri the hairs on underside of tibiae are long, compound and some what matted. If the Central American form which I have is a true Pasipbae\u27, and by Ashmead \u27s description it appears to be, then Pasiphae can be no Collctid even by general habitus, to say nothing more. I shall name this species

The Limits of Faultless Disagreement

Some have argued that the possibility of faultless disagreement gives relativist semantic theories an important explanatory advantage over their absolutist and contextualist rivals. Here I combat this argument, focusing on the specific case of aesthetic discourse. My argument has two stages. First, I argue that while relativists may be able to account for the possibility of faultless aesthetic disagreement, they nevertheless face difficulty in accounting for the intuitive limits of faultless disagreement. Second, I develop a new non-relativist theory which can account for the full range of data regarding faultless disagreement. This view—‘Humean Absolutism’—integrates two of Hume’s central principles from Of the Standard of Taste into a truth-conditional framework, resulting in a non-bivalent theory of aesthetic truth. I argue that Humean Absolutism can underwrite the possibility of faultless disagreement whilst retaining reasonable limits around the phenomenon. I close by relating this positive account of faultless disagreement to broader issues concerning the cognitive role of truth-value gaps. *NB - this is an unpublished paper and is no longer in progress.

Laws for Communicating Parallel Processes

Key Words and Phrases: parallel processes, parallel or asynchronous computations, partial orders of events, Actor theory. CR Categories: 5.21, 5.24, 5.26. This report describes research done at the Artificial Intelligence Laboratory of the Massachusetts Institute of Technology. Support for the laboratory's artificial intelligence research is provided in part by the Advanced Research Projects Agency of the Department of Defense under Office of Naval Research contract N00014-75-C-0522.This paper presents some laws that must be satisfied by computations involving communicating parallel processes. The laws are stated in the context of the actor theory, a model for distributed parallel computation, and take the form of stating plausible restrictions on the histories of parallel computations to make them physically realizable. The laws are justified by appeal to physical intuition and are to be regarded as falsifiable assertions about the kinds of computations that occur in nature rather than as proven theorems in mathematics. The laws are used to analyze the mechanisms by which multiple processes can communicate to work effectively together to solve difficult problems. Since the causal relations among the events in a parallel computation do not specify a total order on events, the actor model generalizes the notion of computation from a sequence of states to a partial order of events. The interpretation of unordered events in this partial order is that they proceed concurrently. The utility of partial orders is demonstrated by using them to express our laws for distributed computation.MIT Artificial Intelligence Laboratory Department of Defense Advanced Research Projects Agenc