arXiv subjects

Ziv Hellman

Publications and source records attributed to Ziv Hellman.

5 recordsLinked to original sources

arXiv2025

Consistent Beliefs without Common Prior

In a strand of the literature, it is assumed that the common prior has full support; that is, every type of every player is assigned positive probability. Morris (1991,1994) established an epistemological-behavioral duality characterisation of the common prior with full support, showing that a finite type space admits such a prior if and only if it contains no acceptable bet. This result forms the basis of the present paper. The paper makes three contributions: (1) The characterisation of Morris (1991,Morris1994) is extended to infinite type spaces. (2) The extension is robust: it does not depend on whether the infinite model applies countably additive or purely additive probabilities as beliefs. (3) The analysis implies that the notion of a real common prior-understood as a single probability distribution or a set of probability distributions-is not necessarily meaningful.

econ.TH↗

arXiv2024

Three Variations on Money Pump, Common Prior, and Trade

We consider finite information structures, and quest for the answer of the question: What is the proper definition of prior? In the single player setting we conclude that a probability distribution is a prior if it is disintegrable, because this definition excludes money pump. In the multiplayer setting our analysis does not boil down to one proper notion of common prior (the multiplayer version of prior). The appropriate notion is a choice of the modeller in this setting. We consider three variants of money pump, each "defines" a notion of common prior. Furthermore, we also consider three variants of trade, each correspond to one of the money pump variants, hence to one of the common prior variants.

econ.TH↗

arXiv2023

Mentors and Recombinators: Multi-Dimensional Social Learning

We study games in which the set of strategies is multi-dimensional, and new agents might learn various strategic dimensions from different mentors. We introduce a new family of dynamics, the recombinator dynamics, which is characterised by a single parameter, the recombination rate r in [0,1]. The case of r = 0 coincides with the standard replicator dynamics. The opposite case of r = 1 corresponds to a setup in which each new agent learns each new strategic dimension from a different mentor, and combines these dimensions into her adopted strategy. We fully characterise stationary states and stable states under these dynamics, and we show that they predict novel behaviour in various applications.

econ.TH↗

arXiv2013

Deludedly Agreeing to Agree

We study conditions relating to the impossibility of agreeing to disagree in models of interactive KD45 belief (in contrast to models of S5 knowledge, which are used in nearly all the agreements literature). We show that even when the truth axiom is not assumed it turns out that players will find it impossible to agree to disagree under fairly broad conditions.

cs.GT↗

arXiv2008

Breaking Out of the Cell: On The Benefits of a New Spreadsheet User-Interaction Paradigm

Contemporary spreadsheets are plagued by a profusion of errors, auditing difficulties, lack of uniform development methodologies, and barriers to easy comprehension of the underlying business models they represent. This paper presents a case that most of these difficulties stem from the fact that the standard spreadsheet user-interaction paradigm - the 'cell-matrix' approach - is appropriate for spreadsheet data presentation but has significant drawbacks with respect to spreadsheet creation, maintenance and comprehension when workbooks pass a minimal threshold of complexity. An alternative paradigm for the automated generation of spreadsheets directly from plain-language business model descriptions is presented along with its potential benefits. Sunsight Modeller (TM), a working software system implementing the suggested paradigm, is briefly described.

cs.HC↗