Formal Sciences
Logic
Proof Theory
ElementScope CategorySub-ItemDefinitionStructural Proof Theory
1. Domain1.1 Scope of the DomainBoundariesThe range of phenomena the science includes and excludes.Studies the structural features of proofs and derivations independent of specific logical connectives; includes sequent structure, structural rules, cut-elimination, normalization; excludes purely semantic truth definitions or model-theoretic validity except where needed to justify structural results.
ScaleThe spatial, temporal, or organizational level at which the science operates (e.g., quantum, cellular, social, cosmic).Operates at the level of formal derivations, inference-rule schemas, proof trees, sequent configurations, context manipulation, and structural transformations.
1.2 Ontological CommitmentsEntitiesThe kinds of things assumed to exist within the domain (particles, organisms, agents, fields, etc.).Sequents, contexts, structural rules (exchange, weakening, contraction), proof trees, derivations, cut steps, substitutions, structural transformations, inference schemas.
PropertiesThe fundamental attributes these entities possess (mass, charge, genotype, preference, etc.).Structural positions, admissibility, derivability, proof height, proof width, normalization behavior, context sensitivity, permutation behavior of rules.
CategoriesThe basic ontological types used to classify domain elements (substances, processes, relations, structures).Sequent structures, structural-rule families, proof transformations, analytic vs. non-analytic steps, cut vs. cut-free derivations, normal vs. non-normal forms.
1.3 State-VariablesVariablesThe measurable or definable properties that describe system conditions.Active sequent, context configuration (Γ, Δ), presence/absence of structural rules, proof depth, branching structure, number of cut occurrences, rule-permutation state.
ParameterizationHow variables encode and represent the system’s state.Representation via structural sequent formats (e.g., Γ ⊢ Δ), context-combinator rules, structural-rule specifications, permutation schemas, cut-rank measures, height and width metrics.
1.4 Admissible IdealizationsSimplificationsConceptual reductions used to make the domain tractable (point masses, rational agents, perfect gases).Idealizing contexts as multisets or sequences; treating structural rules as independent; assuming subformula property; ignoring resource sensitivity in fully structural logics; restricting to cut-free or analytic proofs.
Validity ConditionsThe limits and contexts in which idealizations hold or break down.Idealizations break down in substructural logics (linear, relevant, ordered), systems without contraction/weakening, modal calculi with non-local rules, logics lacking global normalization.
1.5 Domain AssumptionsStructural AssumptionsBackground ontological stances such as determinism, continuity, randomness, discreteness.Proofs are discrete symbolic objects; derivations are finitary; structural rules determine core proof behavior; transformations preserve derivability; normalization is meaningful.
Implicit CommitmentsUnstated but necessary assumptions that shape the field’s conceptual structure.Assumes rule schemas are well-formed; contexts are manipulable under structural constraints; cut-elimination or normalization is desirable or foundational; proof identity depends on structural invariants.
1.6 Internal Coherence RequirementsConsistencyThe demand that domain concepts do not contradict one another.Structural rules cannot trivialize derivability; rule combinations must avoid collapse of logical distinctions; transformations must preserve correctness.
CompatibilityThe requirement that entities, variables, and assumptions fit together into a unified descriptive framework.Requires alignment among sequent structures, structural rules, cut-elimination behavior, permutation principles, and the meta-theoretic framework governing admissibility and normalization.
2. Evidence Layer2.1 Observable PhenomenaObservablesThe aspects of the domain that can produce detectable signals accessible to measurement.Sequent transformations, rule applications, context rearrangements, structural rule effects (exchange, weakening, contraction), cut steps and their eliminations, derivation shapes, normalization sequences.
Detection LimitsThe boundaries of what can be resolved or sensed by current instruments or methods.Limited by proof-search decidability, ability to compute cut-elimination, structural complexity (e.g., large contexts), and the computational cost of checking admissibility of structural rules.
2.2 Measurement SystemsUnitsStandardized quantifications (meters, seconds, volts, decibels, dollars, etc.) necessary for consistent comparison.Proof height, proof width, number of cut occurrences, count of structural-rule applications, normalization length, permutation depth, complexity class of derivability.
InstrumentsDevices and tools (microscopes, spectrometers, sensors, surveys, detectors) used to produce measurements.Automated proof checkers, sequent-calculus provers, structural rule analyzers, normalization engines, theorem provers (Coq, Lean, Isabelle), cut-elimination calculators, proof-graph tools.
2.3 Operational DefinitionsDefinitionsTerms defined by specific measurement procedures, ensuring empirical clarity.Derivability defined by explicit structural-rule sequences; cut defined as a structural inference; cut-rank defined by formula complexity; normalization defined by elimination of non-analytic steps.
ProceduresThe explicit steps required to perform a measurement in a reproducible way.Running structural normalization, applying permutation conversions, collapsing contexts, verifying admissibility, checking cut elimination, generating sequent proofs, tracking proof metrics.
2.4 Data AcquisitionProtocolsFormal processes for gathering data under controlled or standardized conditions.Standardized normalization runs, canonical sequent-construction procedures, controlled permutation experiments, systematic cut-elimination computations, benchmark derivation families.
SamplingRules determining which subset of the domain is measured and how representative it is.Choosing representative sequents, typical derivation patterns, minimal and maximal proof forms, subsets with or without structural rules, normalized vs. non-normalized derivations.
2.5 Data Character & FormatData TypesThe form raw evidence takes (time series, spectra, images, counts, qualitative records).Sequent derivations, context-structured proofs, normalization traces, permutation graphs, cut-elimination sequences, structural-rule application logs, proof trees.
ResolutionThe granularity or precision with which data is captured.Determined by granularity of sequent encoding, specificity of structural-rule tracking, detail level in normalization traces, and the precision of cut-elimination steps.
2.6 Reliability & CalibrationCalibrationAdjustment procedures ensuring instruments produce accurate results.Verifying correct implementation of structural rules, checking validity of permutation conversions, validating normalization algorithms, checking consistency of cut-rank computations.
Error CharacterizationIdentification and quantification of noise, uncertainty, bias, and measurement error.Misapplied structural rules, incorrect context handling, failed normalization, non-terminating transformations, mistaken admissibility assessments, implementation errors in proof assistants.
3. Structural Layer3.1 Patterns & RegularitiesLaws / RelationsStable, repeatable patterns governing how observables behave across conditions.Structural rule behavior (exchange, weakening, contraction), permutation conversions, cut–reduction laws, normalization relations, subformula constraints, analytic proof behavior.
InvariantsQuantities or properties that remain constant under transformations (symmetries, conservation laws).Context invariance under exchange, preservation of derivability under structural permutations, cut-rank monotonicity, subformula property (in analytic systems), invariance of proof identity under rule permutations.
3.2 Causal ArchitectureMechanismsUnderlying processes or structures that produce the observed regularities.Structural-rule operations driving proof transformation, cut-elimination processes, permutation of rules producing normalization, context manipulation mechanisms, absorption and elimination of structural steps.
PathwaysOrganized sequences of interactions forming a causal chain or network.Normalization pathways (cut → reduced form → normal form), structural-rule chains (weakening → contraction → exchange variants), sequent-structure evolution, ordered permutations generating analytic derivations.
3.3 Theoretical VocabularyConceptsCore terms that encode the domain’s structure (force, gene, equilibrium, field).Sequents, contexts, structural rules, cut, cut-rank, normalization, permutation, analyticity, admissibility, proof height/width, proof identity, structural invariants.
ClassificationsTaxonomies, categories, or typologies that organize entities and relations.Classical vs. intuitionistic systems, structural vs. substructural logics, sequent calculi (LK, LJ), calculi with/without structural rules, analytic calculi, deep inference systems, display calculi.
3.4 Formal RepresentationsEquationsMathematical constructs expressing laws, relations, or mechanisms.Cut-reduction equalities, permutation equations (e.g., commuting conversions), structural reflection principles, normal-form characterizations, equality of derivations modulo permutation.
ModelsStructured representations—mathematical, computational, or conceptual—used to predict and explain phenomena.Sequent-calculus proof trees, structural-rule transition graphs, normalization models, cut-free proof frameworks, deep-inference derivation structures, context-combinator models.
3.5 Idealized StructuresSimplified ModelsPurposeful abstractions that capture essential dynamics while omitting irrelevant detail.Analytic calculi with subformula property, cut-free systems, systems with reduced or idealized structural rules, simplified context operators, canonical normalized derivations.
Limit ConditionsRegimes where specific models or approximations hold (classical vs. quantum, linear vs. nonlinear).Breakdowns in substructural logics (linear, relevant, affine), systems where contraction/weakening are disallowed, modal calculi with non-local rules, non-normalizing logics, calculi without global cut-elimination.
3.6 Integrative FrameworksUnifying TheoriesHigher-order structures that connect disparate laws or mechanisms under a coherent whole.Cut-elimination as a unifying structural principle, Gentzen-style proof transformation theory, connection to Curry–Howard (structural correspondence), general proof-theoretic semantics.
Interdisciplinary LinksPoints where the theory connects to adjacent sciences or larger explanatory systems.Links to type theory, lambda calculus, category theory (e.g., monoidal categories for structural behavior), automated reasoning, computational complexity, structural semantics of programming languages.
4. Method Layer4.1 Inquiry DesignExperimental DesignStructured plans for manipulating variables to test causal claims.Manipulating structural rules (adding/removing contraction, weakening, exchange), altering sequent formats, restricting or enabling cut, modifying context-combinators to test effects on derivability and normalization.
Observational DesignSystematic approaches for gathering non-manipulated data (surveys, field studies, natural experiments).Observing normalization behavior, monitoring cut-elimination steps, tracking structural-rule permutations, analyzing proof height/width changes, examining sequent evolution without altering the underlying calculus.
4.2 Testing & ValidationHypothesis TestingProcedures for evaluating whether evidence supports or contradicts specific claims.Testing admissibility of structural rules, testing whether cut-elimination holds, verifying normalization, determining analyticity, checking whether permutation conversions preserve derivability.
ReplicationThe requirement that results be independently reproducible under similar conditions.Reproducing derivations across different structural calculi, independently verifying cut-elimination, replicating normalization sequences, confirming structural-rule behaviors in multiple proof assistants.
4.3 Inference & EvaluationStatistical InferenceRules for drawing conclusions from noisy or incomplete data.Analyzing complexity of normalization, frequency of structural-rule usage, distribution of cut ranks, empirical behavior of proof-search algorithms under structural constraints.
Model ComparisonCriteria (fit, simplicity, predictive accuracy, robustness) used to evaluate competing models.Comparing calculi by normalization strength, cut-elimination power, analytic vs. non-analytic derivations, structural-rule sensitivity, proof-size bounds, computational complexity.
4.4 Error ManagementError AnalysisIdentification and quantification of random and systematic errors.Identifying incorrect context handling, misapplied structural rules, invalid permutations, incorrect cut reductions, failed normalization sequences, and implementation flaws in structural proof engines.
Bias ControlMethods for minimizing subjective, instrumental, or procedural biases.Avoiding heuristic bias in rule ordering, ensuring canonical derivations, controlling implementation-dependent structural transformations, and standardizing normalization strategies.
4.5 Adjudication & RevisionPeer ScrutinyCollective evaluation of claims through critique, review, and debate.Cross-checking structural transformations, reviewing admissibility arguments, comparing normalization proofs, validating sequent configurations, and meta-theoretic critique of rule sets.
Theory RevisionProcedures for modifying, replacing, or discarding models based on new evidence.Updating structural rules, reformulating sequent formats, refining normalization procedures, strengthening or weakening structural assumptions, adjusting calculi to restore cut-elimination or analyticity.
4.6 Integrity ConditionsTransparencyRequirements to disclose methods, data, assumptions, and limitations.Full disclosure of structural rule sets, sequent formats, normalization steps, permutation conversions, cut-elimination proofs, and implementation details of automated proof tools.
Ethical StandardsNorms ensuring responsible conduct in experimentation, data handling, and publication.Ensuring accurate reporting of structural transformations, avoiding hidden assumptions in rule definitions, maintaining reproducible normalization workflows, and clearly documenting system limitations.