A QPTAS for ε-envy-free profit-maximizing pricing on line graphs

  • Authors:
  • Khaled Elbassioni

  • Affiliations:
  • -

  • Venue:
  • ICALP'12 Proceedings of the 39th international colloquium conference on Automata, Languages, and Programming - Volume Part II
  • Year:
  • 2012

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Abstract

We consider the problem of pricing edges of a line graph so as to maximize the profit made from selling intervals to single-minded customers. An instance is given by a set E of n edges with a limited supply for each edge, and a set of m clients, where each client j specifies one interval of E she is interested in and a budget Bj which is the maximum price she is willing to pay for that interval. An envy-free pricing is one in which every customer is allocated (possibly empty) interval maximizing her utility. Recently, Grandoni and Rothvoss (SODA 2011) gave a polynomial-time approximation scheme (PTAS) for the unlimited supply case with running time. By utilizing the known hierarchical decomposition of doubling metrics, we give a PTAS with running time. We then consider the limited supply case, and the notion of -envy-free pricing in which a customer gets an allocation maximizing her utility within an additive error of. For this case we develop an approximation scheme with running time, where $H_e=\frac{B_{\max}(e)}{B_{\min}(e)}$ is the maximum ratio of the budgets of any two customers demanding edge e. This yields a PTAS in the uniform budget case, and a quasi-PTAS for the general case.