document: The two populations ' cellular automata model with predation based on the Penna model In Penna 's -LRB- 1995 -RRB- single-species asexual bit-string model of biological ageing , the Verhulst factor has too strong a restraining effect on the development of the population . Danuta Makowiec gave an improved model based on the lattice , where the restraining factor of the four neighbours take the place of the Verhulst factor . Here , we discuss the two populations ' Penna model with predation on the planar lattice of two dimensions . A cellular automata model containing movable wolves and sheep has been built . The results show that both the quantity of the wolves and the sheep fluctuate in accordance with the law that one quantity increases while the other one decreases
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