<p>For a fixed integer <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(r \ge 1\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>r</mi> <mo>≥</mo> <mn>1</mn> </mrow> </math></EquationSource> </InlineEquation>, a <i>distance-</i><i>r</i> <i>dominating set</i> of a graph <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(G = (V, E)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>G</mi> <mo>=</mo> <mo stretchy="false">(</mo> <mi>V</mi> <mo>,</mo> <mi>E</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> is a subset <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(D \subseteq V\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>D</mi> <mo>⊆</mo> <mi>V</mi> </mrow> </math></EquationSource> </InlineEquation> such that every vertex in <i>V</i> is within distance <i>r</i> from some member of <i>D</i>. Given two distance-<i>r</i> dominating sets <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(D_s\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>D</mi> <mi>s</mi> </msub> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(D_t\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>D</mi> <mi>t</mi> </msub> </math></EquationSource> </InlineEquation> of <i>G</i>, the <span>Distance-</span><i>r</i> <span>Dominating Set Reconfiguration (D</span><i>r</i> <span>DSR)</span> problem asks whether there exists a sequence of distance-<i>r</i> dominating sets transforming <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(D_s\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>D</mi> <mi>s</mi> </msub> </math></EquationSource> </InlineEquation> into <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(D_t\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>D</mi> <mi>t</mi> </msub> </math></EquationSource> </InlineEquation>, where each intermediate member is obtained from its predecessor by applying a given reconfiguration rule exactly once. The case when <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(r = 1\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>r</mi> <mo>=</mo> <mn>1</mn> </mrow> </math></EquationSource> </InlineEquation> has been extensively studied in the literature. We study <span>D</span><i>r</i> <span>DSR</span> for <InlineEquation ID="IEq9"> <EquationSource Format="TEX">\(r \ge 2\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>r</mi> <mo>≥</mo> <mn>2</mn> </mrow> </math></EquationSource> </InlineEquation> under two well-known reconfiguration rules: Token Jumping (<InlineEquation ID="IEq10"> <EquationSource Format="TEX">\(\textsf{TJ}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="sans-serif">TJ</mi> </math></EquationSource> </InlineEquation>), which involves replacing a member of the current D<i>r</i>DS with a non-member, and Token Sliding (<InlineEquation ID="IEq11"> <EquationSource Format="TEX">\(\textsf{TS}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="sans-serif">TS</mi> </math></EquationSource> </InlineEquation>), which involves replacing a member of the current D<i>r</i>DS with an adjacent non-member. For <InlineEquation ID="IEq12"> <EquationSource Format="TEX">\(r = 1\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>r</mi> <mo>=</mo> <mn>1</mn> </mrow> </math></EquationSource> </InlineEquation>, it is known that under either <InlineEquation ID="IEq13"> <EquationSource Format="TEX">\(\textsf{TS}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="sans-serif">TS</mi> </math></EquationSource> </InlineEquation> or <InlineEquation ID="IEq14"> <EquationSource Format="TEX">\(\textsf{TJ}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="sans-serif">TJ</mi> </math></EquationSource> </InlineEquation>, the problem on split graphs is <InlineEquation ID="IEq15"> <EquationSource Format="TEX">\(\texttt{PSPACE}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="monospace">PSPACE</mi> </math></EquationSource> </InlineEquation>-complete. We show that for <InlineEquation ID="IEq16"> <EquationSource Format="TEX">\(r \ge 2\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>r</mi> <mo>≥</mo> <mn>2</mn> </mrow> </math></EquationSource> </InlineEquation>, the problem is in <InlineEquation ID="IEq17"> <EquationSource Format="TEX">\(\texttt{P}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="monospace">P</mi> </math></EquationSource> </InlineEquation>, resulting in an interesting complexity dichotomy. Along the way, we establish nontrivial bounds on the length of a shortest reconfiguration sequence on split graphs when <InlineEquation ID="IEq18"> <EquationSource Format="TEX">\(r = 2\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>r</mi> <mo>=</mo> <mn>2</mn> </mrow> </math></EquationSource> </InlineEquation>, which may be of independent interest. Moreover, we provide observations that lead to polynomial-time algorithms for <span>D</span><i>r</i> <span>DSR</span> for <InlineEquation ID="IEq19"> <EquationSource Format="TEX">\(r \ge 2\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>r</mi> <mo>≥</mo> <mn>2</mn> </mrow> </math></EquationSource> </InlineEquation> on dually chordal graphs under <InlineEquation ID="IEq20"> <EquationSource Format="TEX">\(\textsf{TJ}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="sans-serif">TJ</mi> </math></EquationSource> </InlineEquation> and on cographs under either <InlineEquation ID="IEq21"> <EquationSource Format="TEX">\(\textsf{TS}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="sans-serif">TS</mi> </math></EquationSource> </InlineEquation> or <InlineEquation ID="IEq22"> <EquationSource Format="TEX">\(\textsf{TJ}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="sans-serif">TJ</mi> </math></EquationSource> </InlineEquation>. We also design a linear-time algorithm for solving the problem under <InlineEquation ID="IEq23"> <EquationSource Format="TEX">\(\textsf{TJ}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="sans-serif">TJ</mi> </math></EquationSource> </InlineEquation> on trees. On the negative side, we prove that <span>D</span><i>r</i> <span>DSR</span> for <InlineEquation ID="IEq24"> <EquationSource Format="TEX">\(r \ge 1\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>r</mi> <mo>≥</mo> <mn>1</mn> </mrow> </math></EquationSource> </InlineEquation> remains <InlineEquation ID="IEq25"> <EquationSource Format="TEX">\(\texttt{PSPACE}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="monospace">PSPACE</mi> </math></EquationSource> </InlineEquation>-complete on planar graphs of maximum degree three and bounded bandwidth, improving the degree bound of previously known results. We further demonstrate that the known <InlineEquation ID="IEq26"> <EquationSource Format="TEX">\(\texttt{PSPACE}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="monospace">PSPACE</mi> </math></EquationSource> </InlineEquation>-completeness results under <InlineEquation ID="IEq27"> <EquationSource Format="TEX">\(\textsf{TS}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="sans-serif">TS</mi> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq28"> <EquationSource Format="TEX">\(\textsf{TJ}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="sans-serif">TJ</mi> </math></EquationSource> </InlineEquation> on bipartite graphs and chordal graphs for <InlineEquation ID="IEq29"> <EquationSource Format="TEX">\(r = 1\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>r</mi> <mo>=</mo> <mn>1</mn> </mrow> </math></EquationSource> </InlineEquation> can be extended to <InlineEquation ID="IEq30"> <EquationSource Format="TEX">\(r \ge 2\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>r</mi> <mo>≥</mo> <mn>2</mn> </mrow> </math></EquationSource> </InlineEquation>.</p>

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The complexity of distance-r dominating set reconfiguration

  • Niranka Banerjee,
  • Duc A. Hoang

摘要

For a fixed integer \(r \ge 1\) r 1 , a distance-r dominating set of a graph \(G = (V, E)\) G = ( V , E ) is a subset \(D \subseteq V\) D V such that every vertex in V is within distance r from some member of D. Given two distance-r dominating sets \(D_s\) D s and \(D_t\) D t of G, the Distance-r Dominating Set Reconfiguration (Dr DSR) problem asks whether there exists a sequence of distance-r dominating sets transforming \(D_s\) D s into \(D_t\) D t , where each intermediate member is obtained from its predecessor by applying a given reconfiguration rule exactly once. The case when \(r = 1\) r = 1 has been extensively studied in the literature. We study Dr DSR for \(r \ge 2\) r 2 under two well-known reconfiguration rules: Token Jumping ( \(\textsf{TJ}\) TJ ), which involves replacing a member of the current DrDS with a non-member, and Token Sliding ( \(\textsf{TS}\) TS ), which involves replacing a member of the current DrDS with an adjacent non-member. For \(r = 1\) r = 1 , it is known that under either \(\textsf{TS}\) TS or \(\textsf{TJ}\) TJ , the problem on split graphs is \(\texttt{PSPACE}\) PSPACE -complete. We show that for \(r \ge 2\) r 2 , the problem is in \(\texttt{P}\) P , resulting in an interesting complexity dichotomy. Along the way, we establish nontrivial bounds on the length of a shortest reconfiguration sequence on split graphs when \(r = 2\) r = 2 , which may be of independent interest. Moreover, we provide observations that lead to polynomial-time algorithms for Dr DSR for \(r \ge 2\) r 2 on dually chordal graphs under \(\textsf{TJ}\) TJ and on cographs under either \(\textsf{TS}\) TS or \(\textsf{TJ}\) TJ . We also design a linear-time algorithm for solving the problem under \(\textsf{TJ}\) TJ on trees. On the negative side, we prove that Dr DSR for \(r \ge 1\) r 1 remains \(\texttt{PSPACE}\) PSPACE -complete on planar graphs of maximum degree three and bounded bandwidth, improving the degree bound of previously known results. We further demonstrate that the known \(\texttt{PSPACE}\) PSPACE -completeness results under \(\textsf{TS}\) TS and \(\textsf{TJ}\) TJ on bipartite graphs and chordal graphs for \(r = 1\) r = 1 can be extended to \(r \ge 2\) r 2 .