Given a rank-1 bimatrix game (A,B), i.e., where rank(A+B)=1, we construct a
suitable linear subspace of the rank-1 game space and show that this subspace
is homeomorphic to its Nash equilibrium correspondence. Using this
homeomorphism, we give the first polynomial time algorithm for computing an
exact Nash equilibrium of a rank-1 bimatrix game. In addition, we give a novel
algorithm to enumerate all the Nash equilibria of a rank-1 game and show that a
similar technique may also be applied for finding a Nash equilibrium of any
bimatrix game.
In the Fisher market model, every buyer reveals her preferences over the
available goods in terms of a linear utility function. These utility functions
crucially influence market equilibrium and consequently the payoffs to the
buyers. Motivated by the observation that a buyer may derive a better payoff by
feigning her utility function and thereby manipulating the market equilibrium,
we formulate the {\em Fisher market game} in which buyers strategize by posing
different utility functions while their payoffs are determined with respect to
their true utility functions.