  Quasiliearity is a ubiquitous and questionable assumption in the standard
study of Walrasian equilibria. Quasilinearity implies that a buyer's value for
goods purchased in a Walrasian equilibrium is always additive with goods
purchased with unspent money. It is a particularly suspect assumption in
combinatorial auctions, where buyers' complex preferences over goods would
naturally extend beyond the items obtained in the Walrasian equilibrium.
  We study Walrasian equilibria in combinatorial auctions when quasilinearity
is not assumed. We show that existence can be reduced to an Arrow-Debreu style
market with one divisible good and many indivisible goods, and that a
"fractional" Walrasian equilibrium always exists. We also show that standard
integral Walrasian equilibria are related to integral solutions of an induced
configuration LP associated with a fractional Walrasian equilibrium,
generalizing known results for both quasilinear and non-quasilnear settings.
