pyregg.planar — Planarity

Planarity (PLANAR)

Rare-event estimation for the probability that a Gilbert random geometric graph G(X) is planar:

P(G(X) is planar)

Three estimators are provided: Naïve Monte Carlo, Conditional Monte Carlo, and Importance Sampling Monte Carlo.

References

Hirsch, C., Moka, S. B., Taimre, T., & Kroese, D. P. (2022).

Rare events in random geometric graphs. Methodology and Computing in Applied Probability, 24, 1367–1383.

Moka, S., Hirsch, C., Schmidt, V., & Kroese, D. P. (2025).

Efficient rare-event simulation for random geometric graphs via importance sampling. arXiv:2504.10530.

pyregg.planar.naive_mc(wind_len, kappa, int_range, max_iter=100000000, warm_up=100000, tol=0.001, *, seed=None)[source]

Estimate P(G(X) is planar) using Naïve Monte Carlo.

Parameters:

  • wind_len (float) – Side length of the square observation window [0, wind_len]².

  • kappa (float) – Intensity of the Poisson point process (expected points per unit area).

  • int_range (float) – Interaction range (connection radius) of the Gilbert graph.

  • max_iter (int, optional) – Maximum number of samples. Default is 10**8.

  • warm_up (int, optional) – Minimum samples before checking convergence. Default is 100,000.

  • tol (float, optional) – Stop when estimated RV / n < tol. Default is 0.001.

  • seed (int, optional) – Integer seed for reproducibility (keyword-only). By default no seed is set and results are non-deterministic.

Returns:

  • probability (float) – Estimated rare-event probability P(G(X) is planar).

  • rel_variance (float) – Estimated relative variance of the estimator.

  • n_samples (int) – Number of samples used.

Examples

>>> import pyregg.planar as planar
>>> Z, RV, n = planar.naive_mc(wind_len=10, kappa=1.2, int_range=1.0)
pyregg.planar.conditional_mc(wind_len, kappa, int_range, max_iter=100000000, warm_up=1000, tol=0.001, *, seed=None)[source]

Estimate P(G(X) is planar) using Conditional Monte Carlo.

Parameters:

  • wind_len (float) – Side length of the square observation window [0, wind_len]².

  • kappa (float) – Intensity of the Poisson point process (expected points per unit area).

  • int_range (float) – Interaction range (connection radius) of the Gilbert graph.

  • max_iter (int, optional) – Maximum number of samples. Default is 10**8.

  • warm_up (int, optional) – Minimum samples before checking convergence. Default is 1,000.

  • tol (float, optional) – Stop when estimated RV / n < tol. Default is 0.001.

  • seed (int, optional) – Integer seed for reproducibility (keyword-only). By default no seed is set and results are non-deterministic.

Returns:

  • probability (float) – Estimated rare-event probability P(G(X) is planar).

  • rel_variance (float) – Estimated relative variance of the estimator.

  • n_samples (int) – Number of samples used.

Examples

>>> import pyregg.planar as planar
>>> Z, RV, n = planar.conditional_mc(wind_len=10, kappa=1.2, int_range=1.0)
pyregg.planar.importance_sampling(wind_len, kappa, int_range, grid_res=10, max_iter=100000000, warm_up=100, tol=0.001, *, seed=None)[source]

Estimate P(G(X) is planar) using Importance Sampling Monte Carlo.

Cells where placing a new point would create a K₅ or K₃,₃ minor (detected via a local K₃/K₅ heuristic for blocking, and exact NetworkX planarity test for stopping) are blocked. A likelihood-ratio correction yields an unbiased estimate with substantially lower variance than CMC.

Parameters:

  • wind_len (float) – Side length of the square observation window [0, wind_len]².

  • kappa (float) – Intensity of the Poisson point process (expected points per unit area).

  • int_range (float) – Interaction range (connection radius) of the Gilbert graph.

  • grid_res (int, optional) – Number of grid cells per interaction-range interval. The window is divided into (wind_len / int_range × grid_res)² cells total. Default is 10.

  • max_iter (int, optional) – Maximum number of IS samples. Default is 10**8.

  • warm_up (int, optional) – Minimum samples before checking convergence. Default is 100.

  • tol (float, optional) – Stop when estimated RV / n < tol. Default is 0.001.

  • seed (int, optional) – Integer seed for reproducibility (keyword-only). By default no seed is set and results are non-deterministic.

Returns:

  • probability (float) – Estimated rare-event probability P(G(X) is planar).

  • rel_variance (float) – Estimated relative variance of the IS estimator.

  • n_samples (int) – Number of IS samples used.

Examples

>>> import pyregg.planar as planar
>>> Z, RV, n = planar.importance_sampling(wind_len=10, kappa=1.2, int_range=1.0,
...                                       grid_res=10)