### Abstract

We answer the following question dating back to J. E. Littlewood (1885-1977): Can two lions catch a man in a bounded area with rectifiable lakes? The lions and the man are all assumed to be points moving with at most unit speed. That the lakes are rectifiable means that their boundaries are finitely long. This requirement is to avoid pathological examples where the man survives forever because any path to the lions is infinitely long. We show that the answer to the question is not always "yes" by giving an example of a region R in the plane where the man has a strategy to survive forever. R is a polygonal region with holes and the exterior and interior boundaries are pairwise disjoint, simple polygons. Our construction is the first truly two-dimensional example where the man can survive. Next, we consider the following game played on the entire plane instead of a bounded area: There is any finite number of unit speed lions and one fast man who can run with speed 1 + ϵ for some value ϵ > 0. Can the man always survive? We answer the question in the affirmative for any constant ϵ > 0.

Original language | English |
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Title of host publication | 33rd International Symposium on Computational Geometry, SoCG 2017 |

Number of pages | 556 |

Volume | 77 |

Publisher | Schloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing |

Publication date | 1 Jun 2017 |

Pages | 61-616 |

ISBN (Electronic) | 9783959770385 |

DOIs | |

Publication status | Published - 1 Jun 2017 |

Event | 33rd International Symposium on Computational Geometry, SoCG 2017 - Brisbane, Australia Duration: 4 Jul 2017 → 7 Jul 2017 |

### Conference

Conference | 33rd International Symposium on Computational Geometry, SoCG 2017 |
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Country | Australia |

City | Brisbane |

Period | 04/07/2017 → 07/07/2017 |

Sponsor | University of Queensland |

### Keywords

- Lion and man game
- Pursuit evasion game
- Winning strategy

## Cite this

*33rd International Symposium on Computational Geometry, SoCG 2017*(Vol. 77, pp. 61-616). Schloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing. https://doi.org/10.4230/LIPIcs.SoCG.2017.6