On the Power of Local Orientations

  • Authors:
  • Monika Steinová

  • Affiliations:
  • Department of Computer Science, ETH Zurich, Switzerland

  • Venue:
  • SIROCCO '08 Proceedings of the 15th international colloquium on Structural Information and Communication Complexity
  • Year:
  • 2008

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Abstract

We consider a network represented by a simple connected undirected graph with Nanonymous nodes that have local orientations, i.e. incident edges of each vertex have locally-unique labels --- port names.We define a pre-processing phase that enables a right-hand rule using agent (RH-agent) to traverse the entire graph. For this phase we design an algorithm for an agent that performs the precomputation. The agent will alter the network by modifying the local orientations using a simple operation of exchanging two local labels in each step. We show a polynomial-time algorithm for this precomputation that needs only one pebble and O(logN) memory in the agent.Furthermore we design a similar algorithm where the memory that the agent uses for the precomputation is decreased to O(1). In this case, the agent is not able to perform some operations by itself due to the lack of memory and needs support from the environment.