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topology · SimplicialCohomologyProductTerm

3 accepted declarations. Python and Rust forms, contracts, evidence, failure boundaries, and checked usages are kept together below.

Worked example

The complete checked program Reproduce Fisher's order-five elliptic-function normalization uses this API directly.

# SPDX-License-Identifier: MIT
# Copyright (c) 2026 Benjamin Antieau and Deven Manam
"""Reproduce Fisher's order-five elliptic-function normalization."""

from noether import Q
from noether.commalg import RationalFunctionField, WeilDivisor
from noether.numthy import EllipticCurve, NthPowerClassGroup


def main() -> None:
    coefficients = RationalFunctionField(Q, "lambda")
    parameter = coefficients.generator()
    curve = EllipticCurve(
        coefficients,
        [1 - parameter, -parameter, -parameter, 0, 0],
    )
    point = curve.point(0, 0)
    point.verify_exact_order(5)

    miller = curve.miller_function(point, 5)
    divisor = WeilDivisor(
        curve.underlying_curve,
        [
            (curve.origin().underlying_curve_point.as_closed_point(), 5),
            (point.underlying_curve_point.as_closed_point(), -5),
        ],
    )
    function = divisor.riemann_roch_space().basis[0]
    assert (function / miller.function).as_constant() is not None

    evaluation_at_two = function.evaluate_at((2 * point).underlying_curve_point)
    evaluation_at_four = function.evaluate_at((4 * point).underlying_curve_point)
    assert evaluation_at_two.value is not None
    assert evaluation_at_four.value is not None
    classes = NthPowerClassGroup(coefficients, 5)
    normalization = classes.class_of(evaluation_at_two.value) ** -2 * classes.class_of(
        evaluation_at_four.value
    )
    assert normalization.is_identity()
    print("order 5 verified; Riemann--Roch and Miller agree; normalization is trivial")


if __name__ == "__main__":
    main()

Run it with .venv/bin/python examples/26_elliptic_descent_functions.py.

topology.SimplicialCohomologyProductTerm

One nonzero coefficient in a cohomology basis product.

class SimplicialCohomologyProductTerm

noether::topology::SimplicialCohomologyProductTerm · Direct Rust declaration

pub struct SimplicialCohomologyProductTerm { /* private fields */ }
Contract Value
Guarantee checked deterministic result
Determinism deterministic
Availability default CPU build
Domain implementation crates noether, geom-core, m4rst, m4rste
GIL attached / bounded

topology.SimplicialCohomologyProductTerm.basis

Return the basis recorded by this SimplicialCohomologyProductTerm.

Detailed contract

Global basis index in SimplicialCohomologyRing::basis.

(self) -> int

noether::topology::SimplicialCohomologyProductTerm::basis · Direct Rust declaration

pub fn basis(&self) -> usize
Contract Value
Guarantee checked deterministic result
Determinism deterministic
Availability default CPU build
Domain implementation crates noether, geom-core, m4rst, m4rste
GIL attached / bounded

Executable usage: examples/26_elliptic_descent_functions.py:28 · examples/30_modules_and_resolutions.py:27 · examples/30_modules_and_resolutions.py:28 · examples/30_modules_and_resolutions.py:29 · examples/33_simplicial_cohomology_operations.py:26 · examples/33_simplicial_cohomology_operations.py:27

topology.SimplicialCohomologyProductTerm.coefficient

Return the coefficient recorded by this SimplicialCohomologyProductTerm.

Detailed contract

Exact nonzero coefficient.

(self) -> FiniteFieldElement

noether::topology::SimplicialCohomologyProductTerm::coefficient · Direct Rust declaration

pub fn coefficient(&self) -> &FiniteFieldElement
Contract Value
Guarantee checked deterministic result
Determinism deterministic
Availability default CPU build
Domain implementation crates noether, geom-core, m4rst, m4rste
GIL attached / bounded

Executable usage: examples/17_weighted_power_series.py:19 · examples/22_matroids_and_tutte.py:11 · examples/22_matroids_and_tutte.py:12 · examples/22_matroids_and_tutte.py:13 · examples/33_simplicial_cohomology_operations.py:31 · validation/unit/combin/test_acceptance_workload.py:45