On the existence of dimension zero divisors in algebraic function fields defined over F_q

Let F/F_q be an algebraic function field of genus g defined over a finite field F_q. We obtain new results on the existence, the number and the density of dimension zero divisors of degree g-k in F where k is a positive integer. In particular, for q=2,3 we prove that there always exists a dimension zero divisor of degree \gamma-1 where \gamma is the q-rank of F. We also give a necessary and sufficient condition for the existence of a dimension zero divisor of degree g-k for a hyperelliptic field F in terms of its Zeta function.Comment: 18 page

A (7/2)-Approximation Algorithm for Guarding Orthogonal Art Galleries with Sliding Cameras

Consider a sliding camera that travels back and forth along an orthogonal line segment $s$ inside an orthogonal polygon $P$ with $n$ vertices. The camera can see a point $p$ inside $P$ if and only if there exists a line segment containing $p$ that crosses $s$ at a right angle and is completely contained in $P$. In the minimum sliding cameras (MSC) problem, the objective is to guard $P$ with the minimum number of sliding cameras. In this paper, we give an $O(n^{5/2})$-time $(7/2)$-approximation algorithm to the MSC problem on any simple orthogonal polygon with $n$ vertices, answering a question posed by Katz and Morgenstern (2011). To the best of our knowledge, this is the first constant-factor approximation algorithm for this problem.Comment: 11 page

Do people always pay less than they say? Testbed laboratory experiments with IV and HG values

Hypothetical bias is a long-standing issue in stated preference and contingent valuation studies - people tend to overstate their preferences when they do not experience the real monetary consequences of their decision. This view, however, has been challenged by recent evidence based on the elicitation of induced values (IV) in the lab and homegrown (HG) demand function from different countries. This paper uses an experimental design to assess the extent and relevance of hypothetical bias in demand elicitation exercises for both IV and HG values. For testbed purpose, we use a classic second-price auction to elicit preferences. Comparing the demand curve we elicit in both, hypothetical bias unambiguously (i) vanishes in an induced-value, private good context, and (ii) persists in homegrown values elicitation context. This suggests hypothetical bias in preference elicitation appears to be driven by "preference formation" rather than "preference elicitation". In addition, companion treatments highlight two sources of the discrepancy observed in the HG setting: the hypothetical context leads bidders to underestimate the constraints imposed by their budget limitations, whereas the real context creates pressure leading them to bid "zero" to opt out from the elicitation mechanism. As a result, there is a need for a demand elicitation procedure that helps subjects take the valuation exercise sincerely, but without putting extra pressure on them.Auctions; Demand revelation; Experimental valuation; Hypothetical bias

Do French student really bid sincerely?

Do French Students really bid sincerely in real and hypothetical incentive compatible auctions? Recent evidence suggests they do, which goes counter to most observed bidding behavior in theUnited States, and supports the idea that cultural differences may explain bidding behavior more than economic circumstances. Herein we run a robustness check by exploring bidding behavior in classic Vickrey auction for real and hypothetical values in the two largest cities (Paris and Lyon). Two striking results emerge–(1) French students bid sincerely; and (2) no hypothetical bias exists.Auctions; Demand revelation; Experimental valuation; Hypothetical bias

Preference Elicitation under Oath

Eliciting sincere preferences for non-market goods remains a challenge due to hypothetical bias - the so-called gap between hypothetical monetary values and real economic commitments. The gap arises because people either overstate hypothetical values or understate real commitments or a combination of both. Herein we examine whether the traditional real-world institution of the solenn oath can improve preference elicitation. Applying the social psychology theory on the oath as a truth-telling-commitment device, we ask our bidders to swear on their honour to give honest answers prior to participating in an incentive-compatible second-price auction. Results from our induced valuation testbed treatments suggest the oath-only auctions outperform all other auctions (real, hypothetical, and real-with-oath). In our homegrown valuation treatments eliciting preferences for dolphin protection, the oath-only design induced people to treat as binding both their budget constraint (i.e., lower values on the high end of the value distribution) and participation constraint (i.e., positive values rather than zero bids used to opt out of auction). Our oath-only results are robust to extra training on the auction and to consequential wording about the reason for the oath.Oath, commitment, Vickrey auction, hypothetical bias, induced values, homegrown values.

Do people always pay less than they say? Testbed laboratory experiments with IV and HG values

Hypothetical bias is a long-standing issue in stated preference and contingent valuation studies – people generally overstate their preferences when they do not experience the real monetary consequences of their decision. This view, however, has been challenged by recent evidence based on the elicitation of induced values (IV) in the lab and homegrown (HG) demand function from different countries. This paper uses a two experiments design to assess the extent and relevance of hypothetical bias in demand elicitation exercises for both IV and HG values. For testbed purpose, we use a classic second-price auction to elicit preferences. Comparing the demand curve we elicit in both, hypothetical bias unambiguously (i) vanishes in an induced-value, private good context, and (ii) persists in homegrown values elicitation context. This suggests hypothetical bias in preference elicitation appears to be driven by “preference formation” rather than “preference elicitation”. In addition, companion treatments highlight two sources of the discrepancy observed in the HG setting: the hypothetical context leads bidders to underestimate the constraints imposed by their budget limitations, whereas the real context creates pressure leading them to bid “zero” to opt out from the elicitation mechanism. As a result, there is a need for a demand elicitation procedure that helps subjects take the valuation exercise sincerely, but without putting extra pressure on them.Auctions; Demand revelation; Experimental valuation; Hypothetical bias

Earned wealth, engaged bidders? Evidence from a second price auction

This paper considers whether earned wealth affects bidding behavior in an induced-value second-price auction. We find people bid more sincerely in the auction with earned wealth given monetary incentives; earned wealth did not induce sincere bidding in hypothetical auctions.Auctions; Demand revelation; Experimental valuation; Hypothetical bias; Earned money

Earned Wealth, Engaged Bidders? Evidence from a second price auction

Recent work in experimental economics has explored whether observed behavior depends on whether wealth was windfall or earned. This paper extends this work by considering whether earned wealth ffects bidding behavior in an induced-value second-price auction. We find people bid more sincerely in the auction with earned wealth given monetary incentives; earned wealth did not induce sincere bidding in hypothetical auctions.Auctions; Demand revelation; Experimental valuation; Hypothetical bias; Earned Money

Willingness to Pay of Committed Citizens: A Field Experiment

In this paper, we propose a behavioural approach to determine the extent to which the consumer/citizen distinction affects interpretations of monetary values. We perform a field experiment dealing with air pollution, where some (randomly selected) subjects are given the opportunity to behave politically by signing a petition for environmental protection prior to stating their private preferences in a standard contingent valuation exercise. We show that the petition has the potential to influence respondents' willingness to pay and that whether the effect is negative or positive depends on the degree of (dis)similarity between the petition and the scenario in which willingness to pay are elicited. We interpret the results using the theory of commitment borrowed from social psychology.Field Experiment, Citizen, Consumer, Contingent Valuation, Willingness to pay, Commitment, Air Pollution