Displaying similar documents to “Galvin Tree-Games”

Club-guessing and non-structure of trees

Tapani Hyttinen (2001)

Fundamenta Mathematicae


We study the possibilities of constructing, in ZFC without any additional assumptions, strongly equivalent non-isomorphic trees of regular power. For example, we show that there are non-isomorphic trees of power ω₂ and of height ω · ω such that for all α < ω₁· ω · ω, E has a winning strategy in the Ehrenfeucht-Fraïssé game of length α. The main tool is the notion of a club-guessing sequence.

Hercules versus Hidden Hydra Helper

Jiří Matoušek, Martin Loebl (1991)

Commentationes Mathematicae Universitatis Carolinae


L. Kirby and J. Paris introduced the Hercules and Hydra game on rooted trees as a natural example of an undecidable statement in Peano Arithmetic. One can show that Hercules has a “short” strategy (he wins in a primitively recursive number of moves) and also a “long” strategy (the finiteness of the game cannot be proved in Peano Arithmetic). We investigate the conflict of the “short” and “long” intentions (a problem suggested by J. Nešetřil). After each move of Hercules (trying to kill...

Choice functions and well-orderings over the infinite binary tree

Arnaud Carayol, Christof Löding, Damian Niwinski, Igor Walukiewicz (2010)

Open Mathematics


We give a new proof showing that it is not possible to define in monadic second-order logic (MSO) a choice function on the infinite binary tree. This result was first obtained by Gurevich and Shelah using set theoretical arguments. Our proof is much simpler and only uses basic tools from automata theory. We show how the result can be used to prove the inherent ambiguity of languages of infinite trees. In a second part we strengthen the result of the non-existence of an MSO-definable...

Conway's Games and Some of their Basic Properties

Robin Nittka (2011)

Formalized Mathematics


We formulate a few basic concepts of J. H. Conway's theory of games based on his book [6]. This is a first step towards formalizing Conway's theory of numbers into Mizar, which is an approach to proving the existence of a FIELD (i.e., a proper class that satisfies the axioms of a real-closed field) that includes the reals and ordinals, thus providing a uniform, independent and simple approach to these two constructions that does not go via the rational numbers and hence does for example...

Hercules and Hydra

Martin Loebl (1988)

Commentationes Mathematicae Universitatis Carolinae