Token-Sensitive Enclosure Semantics for Measurement-Bearing Expressions

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Hauptverfasser: Hulak, David B., Ramos, Arthur F., de Queiroz, Ruy J. G. B.
Format: Preprint
Veröffentlicht: 2026
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author Hulak, David B.
Ramos, Arthur F.
de Queiroz, Ruy J. G. B.
author_facet Hulak, David B.
Ramos, Arthur F.
de Queiroz, Ruy J. G. B.
contents Token identity is semantic information for measurement-bearing expressions. Intervals, dimension tags, and token-erased syntax can say what values a measured leaf may take, but they cannot say whether two occurrences name the same observation or two fresh observations. We give a small formal semantics in which each measured leaf carries an interval of possible exact values and an opaque observation-event token. Here "token" means an identity for a measurement event, not a lexical token of the source syntax. The denotation of an expression is its warranted enclosure: the set of exact values still justified by hidden-value environments that assign one value to each observation token and respect the declared intervals. Over this semantics, e -> e' is a claim-tightening judgment, equivalently enclosure containment Encl(e') subseteq Encl(e), while interchangeability is equality of enclosures. The distinction is visible in cancellation, background subtraction, and self-division: reusing one token gives interchangeability with the expected simplified expression, while using distinct tokens gives only one-way containment. We prove that provenance-blind summaries of the kind studied here, preserving intervals, dimension tags, and token-erased syntax, are insufficient to recover the correct rewrite class. The formal results are mechanized in Lean 4 with no sorry or admit placeholders.
format Preprint
id arxiv_https___arxiv_org_abs_2604_07626
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Token-Sensitive Enclosure Semantics for Measurement-Bearing Expressions
Hulak, David B.
Ramos, Arthur F.
de Queiroz, Ruy J. G. B.
Logic in Computer Science
Programming Languages
Token identity is semantic information for measurement-bearing expressions. Intervals, dimension tags, and token-erased syntax can say what values a measured leaf may take, but they cannot say whether two occurrences name the same observation or two fresh observations. We give a small formal semantics in which each measured leaf carries an interval of possible exact values and an opaque observation-event token. Here "token" means an identity for a measurement event, not a lexical token of the source syntax. The denotation of an expression is its warranted enclosure: the set of exact values still justified by hidden-value environments that assign one value to each observation token and respect the declared intervals. Over this semantics, e -> e' is a claim-tightening judgment, equivalently enclosure containment Encl(e') subseteq Encl(e), while interchangeability is equality of enclosures. The distinction is visible in cancellation, background subtraction, and self-division: reusing one token gives interchangeability with the expected simplified expression, while using distinct tokens gives only one-way containment. We prove that provenance-blind summaries of the kind studied here, preserving intervals, dimension tags, and token-erased syntax, are insufficient to recover the correct rewrite class. The formal results are mechanized in Lean 4 with no sorry or admit placeholders.
title Token-Sensitive Enclosure Semantics for Measurement-Bearing Expressions
topic Logic in Computer Science
Programming Languages
url https://arxiv.org/abs/2604.07626