Obviously strategyproof (OSP) mechanisms have recently come to the fore as a tool to deal with imperfect rationality. They, in fact, incentivize people with no contingent reasoning skills to "follow the protocol" and be honest. However, their exact power is still to be determined. For example, even for settings relatively well understood, such as binary allocation problems, it is not clear when optimal solutions can be computed with OSP mechanisms. We here consider this question for the large class of set system problems, where selfish agents with imperfect rationality own elements whose cost can take one among few values. In our main result, we give a characterization of the instances for which the optimum is possible. The mechanism we provide uses a combination of ascending and descending auctions, thus extending to a large class of settings a design paradigm for OSP mechanisms recently introduced in [9]. Finally, we dig deeper in the characterizing property and observe that the set of conditions can be quickly verified algorithmically. The combination of our mechanism and algorithmic characterization gives rise to the first example of automated mechanism design for OSP.
Catering to the incentives of people with limited rationality is a challenging research direction that requires novel paradigms to design mechanisms. Obviously strategy-proof (OSP) mechanisms have recently emerged as the concept of interest to this research agenda. However, the majority of the literature in the area has either highlighted the shortcomings of OSP or focused on the “right” definition rather than on the construction of these mechanisms. Here, we give the first set of tight results on the approximation guarantee of OSP mechanisms for scheduling related machines and a characterization of set system instances for which OSP mechanisms that return optimal solutions exist. By extending the well-known cycle monotonicity technique, we are able to concentrate on the algorithmic component of OSP mechanisms and provide some novel paradigms for their design, when private types belong to a set with few values. In essence, we prove that OSP encompasses careful interleaving of ascending and descending auctions.
Isophytol is a key intermediate in the industrial synthesis of vitamins, produced by selective hydrogenation of dehydroisophytol. This work presents a study of the kinetics of this process in the absence of any solvent. The experimental data were modeled using power-law kinetic expressions and mechanistic models based on Langmuir− Hinshelwood kinetics. The hypothesis of noncompetitive adsorption between hydrogen and organics was chosen in order to describe the changes in the reactivity of the system at varying temperatures (313−353 K) and pressures (5.0−9.0 bar). A simplified approach was used to describe the kinetics of the overhydrogenation reaction to the corresponding alkane. A list of the relevant kinetic and adsorption parameters, the result of an optimization procedure, is reported. The mathematical model, successfully validated, allows the prediction of the influence of the operating conditions and of the addition of quinoline, as reaction modifier, on the selectivity of the process.
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