cppkh-interface

cppkh-interface is a Python package for computing integer Khovanov homology with the C++ cppkh implementation.

The package has no runtime Python-package dependencies. Link crossing signs, PD validation, R1 removal, and nugatory-crossing removal all use the bundled canonical cppkh C++ source and its SageMath-compatible orientation rules.

The package is compatible with the main javakh-interface function:

import cppkh_interface

pd_code = [[1, 5, 2, 4], [3, 1, 4, 6], [5, 3, 6, 2]]
print(cppkh_interface.solve_khovanov(pd_code, de_r1=True, de_k8=True))
print(cppkh_interface.solve_many_khovanov([pd_code, pd_code]))

For a multi-component oriented link, callers can compute several explicit crossing-sign variants without changing the existing APIs:

from cppkh_interface import compute_signed_variants

hopf = [[2, 3, 1, 4], [4, 1, 3, 2]]
results = compute_signed_variants(hopf, [[-1, -1], [1, 1]])
assert len(results) == 2

Each sign row must contain exactly one -1 or 1 for every crossing. This operation deliberately disables PD simplification because removing a crossing would invalidate the positional sign mapping. solve_khovanov and solve_many_khovanov retain their original signatures, inferred-sign behavior, and simplification defaults.

Unlike wrappers that ship a prebuilt DLL or shared object, this package ships the cppkh C++ source file in built distributions and compiles a local executable on first use using only Python's standard library. The compiled executable is cached for later calls.

In the repository checkout, the package does not keep a committed backup copy of the C++ source. The build backend copies ../../src/main.cpp into the package data directory only while the PEP 517 build is running, then removes that temporary copy.

Install

pip install cppkh-interface

A C++14 compiler must be available at runtime. The package looks at CPPKH_INTERFACE_CXX, then CXX, then searches PATH for g++, clang++, or c++. To select a compiler explicitly:

CPPKH_INTERFACE_CXX=clang++ python your_script.py

Windows PowerShell:

$env:CPPKH_INTERFACE_CXX = "C:\path\to\g++.exe"
python your_script.py

Build And Publish

From this directory:

python -m build
poetry publish

Do not use poetry build or poetry publish --build: Poetry's direct builder bypasses the source-synchronizing PEP 517 backend. Build first with python -m build, inspect/test the wheel, then publish the existing artifacts.

For local testing:

poetry run python -m cppkh_interface "[[1,5,2,4], [3,1,4,6], [5,3,6,2]]"