@TechReport{	  it:2003-002,
  author	= {Henrik Bj{\"o}rklund and Sven Sandberg and Sergei
		  Vorobyov},
  title		= {On Combinatorial Structure and Algorithms for Parity
		  Games},
  institution	= {Department of Information Technology, Uppsala University},
  department	= {Computing Science Division},
  year		= {2003},
  number	= {2003-002},
  month		= jan,
  abstract	= {In this paper we identify and systematically explore the
		  combinatorial structure underlying parity and simple
		  stochastic games. We introduce the class of Completely LG
		  (local-global) functions with nice structural properties
		  pertinent to games and allowing for efficient optimization
		  by iterative improvement local search style algorithms. We
		  demonstrate several important combinatorial properties of
		  Completely LG functions, allowing for many optimization
		  algorithms, and establish a relation with the subclass of
		  Completely Unimodal functions, studied by Hammer et al.
		  [1988] Williamson Hoke [1988], and Wiedemann [1985]. We
		  also describe a new, compared to our recent [STACS'2003],
		  subexponential randomized algorithm for CU-functions,
		  CLG-functions, parity, and simple stochastic games, and
		  establish a relation with the class of LP-type problems
		  introduced and investigated by Sharir \& Welzl [1992] and
		  Matousek, Sharir \& Welzl [1992]. }
}