How Old is Our Planet and How Can WeTell?

Abstract: The concept of "Deep Time", and measuring extremely long time, are two of geology's major contributions to our culture. Whereas the recognition of relative ages of events and establishing stratigraphic sequences are part of the foundations of geology, the "absolute" measurement of ages of rocks with reasonable accuracy is an achievement of the last half-century. Such measurement is based on radioactive clocks, in which a parent nuclide decays with a known decay constant to a daughter nuclide. Both "decay clocks" and "accumulation clocks " will be discussed.

Monotonicity and Implementability

Consider a model with finite number of goods, and with buyers with private values and quasi-linear utility functions. A domain of valuation functions for a buyer is a monotonicity domain if every finite-valued monotone randomized allocation rule defined on it is implementable, in the sense that there exists a randomized truth-telling direct mechanism that implements this allocation rule. We prove that a domain of valuations of dimension at least 2 is a monotonicity domain if and only if its closure is convex.

Implementation and Mechanism Design with Evidence (joint work with Bart Lipman)

The standard theory of implementation and mechanism design is limitedin two ways: First it is assumed that the social choice function depends onlyon the pro.le of preferences of the agents over the set of social alternatives.Second, it is assumed that agents cannot support their statements with hardevidence. The general goal of this research is to extend the theory by study-ing a more general model which is not limited in these two ways.

Playing with Biology in silico, or On Comprehensive and Realistic Modeling of Natural Systems

   Abstract: The talk shows the way software and systems engineering, especially of reactive systems, can be applied beneficially to the life sciences. We  will discuss the idea of comprehensive and realistic computerized modeling of biological systems. In comprehensive modeling the main purpose is to understand an entire system in detail, utilizing in the modeling effort  all that is known about the system, and to use that understanding to analyze  and predict behavior in silico.

Color-change in flowers: A silver platter or a cold war?

Abstract: Pollination theories to date hypothesize that plant influence on  pollinator decisions is limited to the level of its attractiveness. In an analytical model, built to analyze selective forces between plants, when color-changing flowers are present, I show that plants can manipulate pollinator decisions in a way that will drive them away from competing species, thus increasing their own fitness. Species employing 'negative advertisement theory' can invade new fields and an evolutionarily stable strategy (ESS) can be attained.

The Crisis of Israeli Private Law: Legal, social and economic implications

The judicial activism of the Israel Supreme Court is usually discussed in terms of the Court's interference in public affairs, especially matters of politics and security, under the guiding principle "all is justiciable." A no less important aspect, however, concerns Israeli private law. Private law is the charter of economic rights of a liberal society.

LEARNING EFFECTIVENESS AND MEMORY SIZE

We quantify the maximal level that a bounded memory machine (or agent) can match (or reproduce) a long string of inputs as a function of a bound k of the length of the input r <= k and the memory size n. The results are derived from the analysis of the repeated game where player 1's strategies are those defined by oblivious automata of size k and player 2's strategies are those defined by automata of size n.

RISK AVERSION, PORTFOLIO DIVERSIFICATION, AND THE DECISION TO GO PUBLIC (...FOR A PRIVATE FIRM...)

Abstract:Risk averse investors should prefer less risky portfolios, all else equal. Markowitz (1952) pioneered the concept of portfolio theory, which launched the modern academic Finance discipline. The idea is that a portfolio that consists of a number of securities has a better mean-variance combination than the same portfolio with just one security. This idea, is essentially behind the development of the modern day capitalism.

EMPIRICAL SIMILARITY AND OBJECTIVE PROBABILITIES

Abstract:We suggest to extend the definition of probability as empirical frequency by the introduction of similarity-weighted frequencies. This formula is axiomatized as follows. A decision maker is asked to express her beliefs by assigning probabilities to certain possible states. We focus on the relationship between her database and her beliefs. We show that, if beliefs given a union of two databases are a convex combination of beliefs given each of the databases, beliefs are a similarity-weighted average of the beliefs induced by each past case.

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