Benjamin Lubin:
Papers
Strategyproof mechanisms provide robust equilibrium with minimal
assumptions about knowledge and rationality but can be unachievable in
combination with other desirable properties such as budget-balance,
stability against deviations by coalitions, and computational
tractability. In the search for maximally-strategyproof mechanisms
that simultaneously satisfy other desirable properties, we introduce a
new metric to quantify the strategyproofness of a mechanism, based on
comparing the payoff distribution, given truthful reports, against
that of a strategyproof reference mechanism that solves a problem
relaxation.Focusing on combinatorial exchanges, we demonstrate that
the metric is informative about the eventual equilibrium, where simple
regretbased metrics are not, and can be used for online selection of
an effective mechanism.
As data-center energy consumption continues to rise, efficient power
management is becoming increasingly important. In this work, we
examine the use of a novel market mechanism for finding the right
balance between power and performance. The market enables a separation
between a buyer side that strives to maximize performance and a seller
side that strives to minimize power and other costs. A concise and
scalable description language is defined for agent preferences that
admits a mixed-integer program for computing optimal
allocations. Experimental results demonstrate the robustness,
flexibility, practicality and scalability of the architecture.
We present the design and analysis of the first fully expressive,
iterative combinatorial exchange (ICE). The exchange incorporates a
tree-based bidding language (TBBL) that is concise and expressive for
CEs. Bidders specify lower and upper bounds in TBBL on their value for
different trades and refine these bounds across rounds. These bounds
allow price discovery and useful preference elicitation in early
rounds, and allow termination with an efficient trade despite partial
information on bidder valuations. All computation in the exchange is
carefully optimized to exploit the structure of the bid-trees and to
avoid enumerating trades. A proxied interpretation of a
revealed-preference activity rule, coupled with simple linear prices,
ensures progress across rounds. The exchange is fully implemented, and
we give results demonstrating several aspects of its scalability and
economic properties with simulated bidding strategies.
Combinatorial exchanges (CEs) facilitate trade between multiple buyers
and sellers that need to express complex preferences on bundles of
items. We present the first design for an iterative combinatorial
exchange (ICE). The exchange incorporates a tree-based bidding
language that is concise and expressive for CEs. Winner-determination
is directly formulated in terms of the structure of this language. The
main innovation is that bidders interact with proxy agents, and
specify lower and upper valuations for trades by annotating the tree
with value intervals. The design is entirely symmetric, handling
buyers, sellers and mixed buyers and sellers. The proxy approach
facilitates early price discovery and ensures useful preference
elicitation even in early rounds. Constraint generation is used to
generate linear prices without enumerating all possible trades. A
proxied interpretation of a revealed-preference activity rule ensures
progress. At termination, a VCG-based payment scheme that has been
shown to reduce opportunities for bargaining and strategic behavior is
used to determine payments. The exchange is fully implemented,
running, and in a validation phase.
We present a novel tree-based logical bidding language, TBBL, for
preference elicitation in combinatorial exchanges (CEs). TBBL provides
new expressiveness for two-sided markets with agents that are both
buying and selling goods. Moreover, the rich semantics of TBBL allow
the language to capture new structure, making it exponentially more
concise than OR* and LGB for preferences that are realistic in
important domains for CEs. With simple extensions TBBL can subsume
these earlier languages. TBBL can also explicitly represent partial
information about valuations. The language is designed such that the
structure in TBBL bids can be concisely captured directly in
mixed-integer programs for the allocation problem. We illustrate TBBL
through examples drawn from domains to which it can be (and is being)
applied, and motivate further extensions we are currently
pursuing.
The primary benefit of genetic schedulers is that they can often
construct high quality schedules for long term scheduling. A common
cost associated with genetic scheduling is that it may take tremendous
amounts of time and computing power to produce high quality schedules,
and these costs can make genetic scheduling impractical for many
dynamic environments. The Air Crew Scheduler (ACS) system is built to
crew tours for multiple squadrons in the United States Air Force. The
system is built around a genetic scheduling engine that is designed to
work alongside human schedulers to make crew assignments to tours.
The crew scheduling problem itself is constraint laden and requires
rapid schedule updates for changes to crew member information and tour
changes. This paper provides a high-level overview of the problem and
its constraints. We provide a design overview of the genetic
scheduler that has been constructed to rapidly schedule in this
dynamic setting.
Newspaper production is a complex task with
numerous subtasks, each performed by different people. Many of these
subtasks can be started independently, but cannot be finished without
the completion of their dependent tasks. Because newspapers are
produced under tight deadlines, taking advantage of this parallelism
is important, but it comes at the price of many repeated changes to
the layout. These changes occur when articles are added or dropped,
lengths are changed, advertising space changes etc. This thesis
presents a new approach to layout, where the user specifies
constraints on the text boxes, rather than absolute position, allowing
the layout to adapt highly sensitively to content changes. The
constraints are represented in a mass-spring model that is evaluated
in real time. This model is chosen (over other potentially more
'optimizing' solutions) so that immediate feedback can be provided to
the user in an intuitive way, allowing him/her to update the
constraints appropriately.