Structural Impossibility of Antichain-Lattice Partial Information Decomposition

Fuente: arXiv
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Main Authors: Lyu, Aobo, Clark, Andrew, Raviv, Netanel
Format: Preprint
Published: 2026
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_version_ 1866910129400578048
author Lyu, Aobo
Clark, Andrew
Raviv, Netanel
author_facet Lyu, Aobo
Clark, Andrew
Raviv, Netanel
contents Partial Information Decomposition (PID) represents multivariate mutual information via antichain-lattice that aims to specify which source groups can recover which informational components of a target. For three or more sources, widely desired PID axioms become mutually incompatible. This is often treated as an axiomatic tuning issue. This paper argues that the obstruction is representational, rooted in the antichain indexing itself, so that purely axiomatic adjustments within an antichain-lattice structure cannot resolve it in general. We first introduce System Information Decomposition (SID) for the special target-free three-variable setting, obtaining a self-consistent entropy decomposition with an operational redundancy definition. More fundamentally, we then show that for general multivariate PID, there is no universal rule that recovers the decomposed mutual information from the antichain-indexed information atoms. In particular, two systems can share identical atoms regardless of any axioms while having different mutual information. These results reveal the limits of antichain-lattice and motivate relation-based foundations for multivariate information measures.
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id arxiv_https___arxiv_org_abs_2604_03869
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Structural Impossibility of Antichain-Lattice Partial Information Decomposition
Lyu, Aobo
Clark, Andrew
Raviv, Netanel
Information Theory
Partial Information Decomposition (PID) represents multivariate mutual information via antichain-lattice that aims to specify which source groups can recover which informational components of a target. For three or more sources, widely desired PID axioms become mutually incompatible. This is often treated as an axiomatic tuning issue. This paper argues that the obstruction is representational, rooted in the antichain indexing itself, so that purely axiomatic adjustments within an antichain-lattice structure cannot resolve it in general. We first introduce System Information Decomposition (SID) for the special target-free three-variable setting, obtaining a self-consistent entropy decomposition with an operational redundancy definition. More fundamentally, we then show that for general multivariate PID, there is no universal rule that recovers the decomposed mutual information from the antichain-indexed information atoms. In particular, two systems can share identical atoms regardless of any axioms while having different mutual information. These results reveal the limits of antichain-lattice and motivate relation-based foundations for multivariate information measures.
title Structural Impossibility of Antichain-Lattice Partial Information Decomposition
topic Information Theory
url https://arxiv.org/abs/2604.03869