Relational Theory Of Expression (RTE): Quasilocal Manifestation, Reconstruction, and Operational Equivalence

Relational Theory of Expression (RTE) proposes a new conceptual framework in which physics is understood not primarily as a theory of independently existing objects, but as a theory of the conditions under which physical content becomes expressible within a quasilocal domain. The central idea is that the physically accessible object is not an isolated state x, but an operational equivalence class [x]ᴰ, induced by an expression map Eᴰ : Sphys → Sobs(D). This naturally leads to x₁ ∼ᴰ x₂ ⇔ Eᴰ(x₁) = Eᴰ(x₂) and to the factorization of physical descriptions through operationally meaningful quotient spaces. The framework separates definitions, theorems, physical postulates, hypotheses, and interpretations, allowing philosophical motivation and mathematical structure to evolve independently while remaining logically consistent. Beyond operational equivalence, RTE introduces a rigorous distinction between manifestation, reconstruction, and ontology. Past and future are treated as compatible reconstructions, represented by the space of histories Γᴰ(d) rather than directly observable entities. Local physical descriptions are organized through presheaf and sheaf structures, where restriction maps connect overlapping domains and failures of gluing provide a natural mathematical language for contextuality, boundary effects, and reconstruction limits. Within this framework, auxiliary constructions such as B⁴ are treated with explicit type discipline: they may exist as mathematical fillings or variational tools without being promoted to physically existing regions of spacetime. The programme therefore distinguishes mathematical existence from physical existence in a precise and operationally useful way. The present work is intended as the foundational paper of a broader research programme connecting quasilocal cosmology, information theory, observer-dependent reconstruction, and categorical mathematics. Rather than proposing a new dynamical law, it establishes a minimal structural language in which later developments—such as the DRD information framework, quasilocal B⁴ cosmology, boundary variational principles, and observational cosmology—can be formulated within a common conceptual architecture. The guiding principle is that physics studies invariant structures of expressibility, while the objects of physics emerge as stable relational manifestations rather than self-subsistent entities. This first version is therefore conceived as the opening movement of a larger mathematical programme, providing a disciplined foundation for subsequent theoretical and empirical developments.