procela 1.0.1

Epistemic Governance in Mechanistic Simulations Under Structural Uncertainty

Procela

Epistemic Governance in Mechanistic Simulations Under Structural Uncertainty

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📖 Overview

Procela is a research-grade Python framework that treats simulation as an epistemic process rather than a fixed model. Traditional mechanistic simulations assume a fixed ontology—variables, causal relationships, and resolution mechanisms are specified before execution and remain static. This assumption fails when the true causal structure of a system is contested, unidentifiable, or subject to change.

Procela solves this by enabling simulations to question their own assumptions at runtime.

Core abstractions

Abstraction	Description
Variables	Epistemic authorities that maintain complete hypothesis memory with cryptographic source tracking. Resolve competing claims via policies (weighted voting, highest confidence, median, etc).
Mechanisms	Causal units that read variables and propose hypotheses—they never mutate state directly. Each mechanism encodes a scientific theory (ontology) and attaches confidence scores to its predictions.
Governance (Invariants & Hooks)	First-class units that observe epistemic signals (coverage, fragility, conflict, etc) and can mutate system topology at runtime. Follow the scientific method pattern: detect → hypothesize → experiment → evaluate → conclude. Failed experiments can be automatically reverted.
Epistemic signals	User-defined observables computed from variable memories. Standard signals: coverage (prediction accuracy), policy fragility (intervention disagreement), recent error (rolling prediction error).
Executive	Orchestrates the entire simulation: executes mechanisms, resolves variables, evaluates invariants & hooks at PRE/RUNTIME/POST phases. Maintains random state, step counter, and complete system history.

Why Procela?

• Domain-agnostic: No built-in epistemic metrics—you define what signals matter. Applicable to epidemiology, climate science, economics, robotics, and beyond.
• Fully auditable: Every hypothesis is permanently recorded with cryptographic source tracking. Every governance action leaves a trace. Complete reproducibility.
• Structural mutability: Add, remove, enable, or disable mechanisms during execution. Change resolution policies on the fly. The model is a living hypothesis.
• Scientific method pattern: Governance follows detect → hypothesize → experiment → evaluate → conclude. The system learns from its own interventions.

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🚀 Quick start

Installation

# From PyPI (stable)
pip install procela

# From GitHub (development)
pip install git+https://github.com/kvernet/procela.git

Minimal Example

import numpy as np
from procela import (
    Executive,
    Mechanism,
    Variable,
    RangeDomain,
    VariableRecord,
    WeightedVotingPolicy
)

# Create a variable
X = Variable("X", RangeDomain(0, 100), policy=WeightedVotingPolicy())
X.init(VariableRecord(50.0, confidence=1.0))

# Define a mechanism
class MyMechanism(Mechanism):
    def __init__(self):
        super().__init__(reads=[X], writes=[X])

    def transform(self):
        val = self.reads()[0].value + np.random.normal(0, 1)
        self.writes()[0].add_hypothesis(VariableRecord(val, confidence=0.8, source=self.key()))

# Run simulation
executive = Executive(mechanisms=[MyMechanism()])
executive.run(steps=10)
print(f"Final value: {X.value:.2f}")

Governance Example

from procela import (
    HighestConfidencePolicy,
    SystemInvariant,
    InvariantPhase,
    InvariantViolation,
    VariableSnapshot,
    KeyAuthority
)

# Define a governance invariant
class FragilityInvariant(SystemInvariant):
    def __init__(self, threshold=0.5):
        self.threshold = threshold
        self.switched = False

        def check(snapshot: VariableSnapshot):
            confidences = [KeyAuthority.resolve(view.key).confidence for view in snapshot.views]
            if confidences and max(confidences) - min(confidences) > self.threshold:
                return False  # Violation — fragility detected
            return True

        def handle(invariant: InvariantViolation, snapshot: VariableSnapshot):
            if not self.switched:
                print("Fragility detected! Switching to highest-confidence policy")
                X.policy = HighestConfidencePolicy()
                self.switched = True

        super().__init__(
            "FragilityInvariant",
            condition=check,
            on_violation=handle,
            phase=InvariantPhase.RUNTIME,
            message="Fragility invariant violation"
        )

# Add invariant to executive
executive.add_invariant(FragilityInvariant())

executive.run(steps=10)
print(f"Final value: {X.value:.2f}")

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📚 Case study: AMR spread in hospital networks

We demonstrate Procela on antimicrobial resistance (AMR) spread with three competing ontology families:

Ontology	Equation	Intervention
Contact	$C_{t+1} = C_t + \beta_C C_t (1 - \eta_C \mathbf{1}_{I=1})$	Isolation
Environmental	$C_{t+1} = C_t + \beta_E E_t (1 - \eta_E \mathbf{1}_{I=2})$	Cleaning
Selection	$C_{t+1} = C_t + \beta_S A_t (1 - \eta_S \mathbf{1}_{I=3})$	Stewardship

Results

Governance strategy	Error reduction	Regret improvement
Policy fragility	-1.63%	-9.8%
Coverage decay	20.42%	35.5%
Structural probe	9.31	69.0%
All combined	8.18%	61.6%

Key finding: The case study has revealed a fundamental trade-off:

• Prediction-optimal $\neq$ decision-optimal
• Coverage decay makes better predictions but modest decisions (+20.42%, C.E=35.5%)
• Probe makes better decisions but only modestly improves predictions (+9.31%, C.E=69.0%)

Consider hybrid — probe for information, coverage for prediction.

Topology dynamics

Procela ensures complete auditability. The memories of variables can be used to visualize the topology dynamics. As illustrated in the following figure, the topology evolution for each governance in the AMR study is illustrated. The contact family has three mechanisms, while the environmental and selection families have four each. In total, the AMR case study has eleven competing mechanisms that governance restructures over time.

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🛠️ Development

Setup development environment

git clone https://github.com/kvernet/procela.git
cd procela
python -m venv .venv
source .venv/bin/activate  # On Windows: .venv\Scripts\activate
make dev-install

Available makefile targets

Target	Description
make install	Install package and dependencies
make dev-install	Install with development dependencies
make lint	Run linters (ruff, black)
make type-check	Run mypy type checking
make test	Run pytest with coverage
make pre-commit	Run all checks before committing
make docs	Build documentation
make clean	Clean build artifacts

Code style

• Formatting: Black (line length 88)
• Linting: Ruff
• Type checking: Mypy (strict mode)
• Testing: Pytest with coverage (target 100%)

make pre-commit  # Run all checks

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📖 Documentation

• User guide: https://docs.procela.org/
• API reference: https://docs.procela.org/api/
• Examples: https://docs.procela.org/examples

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🤝 Contributing

We welcome contributions! Please see:

• CONTRIBUTING.md for detailed guidelines
• AUTHORS.txt for the list of contributors

Areas where contributions are especially welcome:

• Additional governance invariants (regret-based, multi-objective)
• Performance optimizations for large-scale simulations
• New domain case studies (climate, economics, robotics)
• Documentation improvements and tutorials
• Visualization tools for audit trails

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📄 Citation

If you use Procela in your research, please cite:

@software{procela_2026,
    title={Procela: Epistemic Governance in Mechanistic Simulations Under Structural Uncertainty},
    author={Kinson Vernet},
    year={2026},
    eprint={2604.00675},
    archivePrefix={arXiv},
    primaryClass={physics.comp-ph},
    url={https://arxiv.org/abs/2604.00675},
}

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📋 License

Procela is licensed under the Apache License 2.0. See LICENSE for details.

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🙏 Acknowledgments

We thank the open-source community for Pyodide, NumPy, and the Python scientific ecosystem.

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📬 Contact

• Email: [e-mail]
• GitHub Issues: github.com/kvernet/procela/issues

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_{Built with ❤️ for epistemic governance in simulation.}

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