Embedding#

Provides functions that map binary quadratic models (BQM) and samples between a source graph and a target graph.

For an introduction to minor-embedding, see the Minor Embedding section.

minorminer is a heuristic tool for minor embedding: given a minor and target graph, it tries to find a mapping that embeds the minor into the target.

Heuristically attempt to find a minor-embedding of source graph S into a target graph T.

Minor-embedding in target graphs with Chimera, Pegasus, and Zephyr topology.

`chimera.find_clique_embedding`(k[, m, n, t, ...])	Find an embedding for a clique in a Chimera graph.
`chimera.find_biclique_embedding`(a, b[, m, ...])	Find an embedding for a biclique in a Chimera graph.
`chimera.find_grid_embedding`(dim, m[, n, t])	Find an embedding for a grid in a Chimera graph.
`pegasus.find_clique_embedding`(k[, m, ...])	Find an embedding for a clique in a Pegasus graph.
`pegasus.find_biclique_embedding`(a, b[, m, ...])	Find an embedding for a biclique in a Pegasus graph.
`zephyr.find_clique_embedding`(k[, m, ...])	Find an embedding for a clique in a Zephyr graph.
`zephyr.find_biclique_embedding`(a, b[, m, ...])	Find an embedding for a biclique in a Zephyr graph.

`embed_bqm`(source_bqm[, embedding, ...])	Embed a binary quadratic model onto a target graph.
`embed_ising`(source_h, source_J, embedding, ...)	Embed an Ising problem onto a target graph.
`embed_qubo`(source_Q, embedding, target_adjacency)	Embed a QUBO onto a target graph.

`diagnose_embedding`(emb, source, target)	Diagnose a minor embedding.
`is_valid_embedding`(emb, source, target)	A simple (bool) diagnostic for minor embeddings.
`verify_embedding`(emb, source, target[, ...])	A simple (exception-raising) diagnostic for minor embeddings.

Utility functions for calculating chain strength.

`uniform_torque_compensation`(bqm[, ...])	Set chain strength to compensate for chain-breaking torque.
`scaled`(bqm[, embedding, prefactor])	Set chain strength that is scaled to the problem's bias range.

`adjacency_to_edges`(adjacency)	Convert an adjacency object to an edge iterator.
`chain_to_quadratic`(chain, target_adjacency, ...)	Determine the quadratic biases that induce the given chain.
`draw_chimera_bqm`(bqm[, width, height])	Represent a binary quadratic model as a Chimera graph.
`edgelist_to_adjacency`(edgelist)	Convert an iterator of edges to an adjacency dict.

EmbeddedStructure(target_edges, embedding)

Embedding structure for a target graph and minor embedding.

For all properties and methods, see the EmbeddedStructure class.

`EmbeddedStructure.chain_edges`(u)	Iterate over edges contained in the chain for variable `u`.
`EmbeddedStructure.chain_strength`	Return the chain strength selected for embedding.
`EmbeddedStructure.embed_bqm`(source_bqm[, ...])	Embed a binary quadratic model onto a target graph.
`EmbeddedStructure.interaction_edges`(u, *args)	Iterate over edges between the chains for variables `u` and `v`.
`EmbeddedStructure.max_chain_length`	Maximum chain length in the embedding.

Unembedding#

unembed_sampleset(target_sampleset, ...[, ...])

Unembed a sample set.

`broken_chains`(samples, chains)	Find the broken chains for the given samples.
`chain_break_frequency`(samples_like, embedding)	Determine the frequency of chain breaks in the given samples.

Unembedding samples with broken chains.

`discard`(samples, chains)	Discard broken chains.
`majority_vote`(samples, chains)	Unembed samples using the most common value for broken chains.
`MinimizeEnergy`(bqm, embedding)	Unembed samples by minimizing local energy for broken chains.
`weighted_random`(samples, chains)	Unembed samples using weighed random choice for broken chains.

target_to_source(target_adjacency, embedding)

Derive the source adjacency from an embedding and target adjacency.

`EmbeddingError`	Base class for all embedding exceptions.
`MissingChainError`(snode)	Raised if a node in the source graph has no associated chain.
`ChainOverlapError`(tnode, snode0, snode1)	Raised if two source nodes have an overlapping chain.
`DisconnectedChainError`(snode)	Raised if a chain is not connected in the target graph.
`InvalidNodeError`(snode, tnode)	Raised if a chain contains a node not in the target graph.
`MissingEdgeError`(snode0, snode1)	Raised when two source nodes sharing an edge to not have a corresponding edge between their chains.