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The Berlin Safe House Puzzle: Spycraft via Interval Graphs

Authors Gennaro Cordasco , Luisa Gargano , Adele Anna Rescigno

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Subject Classification

ACM Subject Classification
  • Theory of computation → Problems, reductions and completeness
  • Theory of computation → Approximation algorithms analysis
Keywords
  • Interval Graphs
  • Watching-System
  • Approximate Algorithms

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Abstract

We propose a gamified application of the {Identifying Code} problem on {Interval Graphs}, framed as a high-stakes Cold War counter-intelligence operation. We present a polynomial-time algorithm to assign "Listening Devices" (bugs) to "Safe Houses" (intervals) so that every safe house is uniquely identifiable by its bug signature. While the problem is NP-hard on several graph classes, including chordal and bipartite graphs, the interval-graph structure allows us to compute a 2-approximate solution efficiently.

Cite As Get BibTex

Gennaro Cordasco, Luisa Gargano, and Adele Anna Rescigno. The Berlin Safe House Puzzle: Spycraft via Interval Graphs. In 13th International Conference on Fun with Algorithms (FUN 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 366, pp. 13:1-13:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026) https://doi.org/10.4230/LIPIcs.FUN.2026.13

Author Details

Gennaro Cordasco
  • Dipartimento di Informatica, Università degli Studi di Salerno, Fisciano, Italy
Luisa Gargano
  • Dipartimento di Informatica, Università degli Studi di Salerno, Fisciano, Italy
Adele Anna Rescigno
  • Dipartimento di Informatica, Università degli Studi di Salerno, Fisciano, Italy

Funding

This work was partially supported by project SERICS (PE00000014) under the MUR National Recovery and Resilience Plan funded by the European Union - NextGenerationEU.

References

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