quimb.experimental.belief_propagation.l1bp

Module Contents

Classes

L1BP

Lazy 1-norm belief propagation. BP is run between groups of tensors

Functions

contract_l1bp(tn[, max_iterations, tol, site_tags, ...])

Estimate the contraction of tn using lazy 1-norm belief propagation.
class quimb.experimental.belief_propagation.l1bp.L1BP(tn, site_tags=None, damping=0.0, update='sequential', local_convergence=True, optimize='auto-hq', message_init_function=None, **contract_opts)

Bases: quimb.experimental.belief_propagation.bp_common.BeliefPropagationCommon

Lazy 1-norm belief propagation. BP is run between groups of tensors defined by site_tags. The message updates are lazy contractions.

Parameters:

  • tn (TensorNetwork) – The tensor network to run BP on.

  • site_tags (sequence of str, optional) – The tags identifying the sites in tn, each tag forms a region, which should not overlap. If the tensor network is structured, then these are inferred automatically.

  • damping (float, optional) – The damping parameter to use, defaults to no damping.

  • update ({'parallel', 'sequential'}, optional) – Whether to update all messages in parallel or sequentially.

  • local_convergence (bool, optional) – Whether to allow messages to locally converge - i.e. if all their input messages have converged then stop updating them.

  • optimize (str or PathOptimizer, optional) – The path optimizer to use when contracting the messages.

  • contract_opts – Other options supplied to cotengra.array_contract.

iterate(tol=5e-06)
contract(strip_exponent=False)
normalize_messages()

Normalize all messages such that for each bond <m_i|m_j> = 1 and <m_i|m_i> = <m_j|m_j> (but in general != 1).

quimb.experimental.belief_propagation.l1bp.contract_l1bp(tn, max_iterations=1000, tol=5e-06, site_tags=None, damping=0.0, update='sequential', local_convergence=True, optimize='auto-hq', strip_exponent=False, info=None, progbar=False, **contract_opts)

Estimate the contraction of tn using lazy 1-norm belief propagation.

Parameters:

  • tn (TensorNetwork) – The tensor network to contract.

  • max_iterations (int, optional) – The maximum number of iterations to perform.

  • tol (float, optional) – The convergence tolerance for messages.

  • site_tags (sequence of str, optional) – The tags identifying the sites in tn, each tag forms a region. If the tensor network is structured, then these are inferred automatically.

  • damping (float, optional) – The damping parameter to use, defaults to no damping.

  • update ({'parallel', 'sequential'}, optional) – Whether to update all messages in parallel or sequentially.

  • local_convergence (bool, optional) – Whether to allow messages to locally converge - i.e. if all their input messages have converged then stop updating them.

  • optimize (str or PathOptimizer, optional) – The path optimizer to use when contracting the messages.

  • progbar (bool, optional) – Whether to show a progress bar.

  • strip_exponent (bool, optional) – Whether to strip the exponent from the final result. If True then the returned result is (mantissa, exponent).

  • info (dict, optional) – If specified, update this dictionary with information about the belief propagation run.

  • contract_opts – Other options supplied to cotengra.array_contract.