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Journals and Conferences
Cellular automata are simple model for the study of complex phenomena produced by simple local interactions. They consist of a regular lattice of cells. Each cell contain finite automaton which has a state chosen from a finite set of states. Updates are made according to a local rule which takes into account the current state of the cell and those of a… (More)
In this paper, we study the structure of the set of tilings produced by any given tile-set. For better understanding this structure, we address the set of finite patterns that each tiling contains. This set of patterns can be analyzed in two different contexts: the first one is combinatorial and the other topological. These two approaches have independent… (More)
The Game of Life was created by J.H. Conway. One of the main features of this game is its universality. We prove in this paper this universality with respect to several computational models: boolean circuits, Turing machines, and two-dimensional cellular automata. These diierent points of view on Life's universality are chosen in order to clarify the… (More)
We prove that de6nitions of number-conserving cellular automata found in literature are equivalent. A necessary and su9cient condition for cellular automata to be number-conserving is proved. Using this condition, we give a quasi-linear time algorithm to decide number-conservation. c © 2002 Elsevier Science B.V. All rights reserved.
An aperiodic tile set was first constructed by R. Berger while proving the undecidability of the domino problem. It turned out that aperiodic tile sets appear in many fields, ranging from logic (the Entscheidungsproblem) to physics (quasicrystals). We present a new construction of an aperiodic tile set that is based on Kleene’s fixed-point construction… (More)
In this paper we use fixed point tilings to answer a question posed by Michael Hochman and show that every one-dimensional effectively closed subshift can be implemented by a local rule in two dimensions. The proof uses the fixed-point construction of an aperiodic tile set and its extensions.
The generation of murine mast cells is supported by several cytokines, and mast cell lines are frequently established in long-term cultures of normal murine marrow cells. In contrast, growth of human mast cells was initially dependent on coculture with murine fibroblasts. The growth factor produced by murine fibroblasts and required to observe… (More)