Reconstruction from smaller cards

Journal Article (2025)
Author(s)

Carla Groenland (TU Delft - Discrete Mathematics and Optimization)

Tom Johnston (University of Oxford)

Alex Scott (University of Oxford)

Jane Tan (University of Oxford)

Research Group
Discrete Mathematics and Optimization
DOI related publication
https://doi.org/10.1007/s11856-025-2858-3
More Info
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Publication Year
2025
Language
English
Research Group
Discrete Mathematics and Optimization
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Abstract

The ℓ-deck of a graph G is the multiset of all induced subgraphs of G on ℓ vertices. We say that a graph is reconstructible from its ℓ-deck if no other graph has the same ℓ-deck. In 1957, Kelly showed that every tree with n ≥ 3 vertices can be reconstructed from its (n − 1)-deck, and Giles strengthened this in 1976, proving that trees on at least 6 vertices can be reconstructed from their (n − 2)-decks. Our main theorem states that trees are reconstructible from their (n − r)-decks for all r ≤ n/9 + o(n), making substantial progress towards a conjecture of Nýdl from 1990. In addition, we can recognise the connectedness of a graph from its ℓ-deck when ℓ ≥ 9n/10, and reconstruct the degree sequence when ℓ≥2nlog(2n). All of these results are significant improvements on previous bounds.