File embedding.hpp

Defines

DIAGNOSE(X)

namespace find_embedding

template <typename embedding_problem_t>
class find_embeddingembedding

#include <embedding.hpp>

This class is how we represent and manipulate embedding objects, using as much encapsulation as possible.

We provide methods to view and modify chains.

Public Functions

find_embedding::embeddingembedding(embedding_problem_t &e_p)

constructor for an empty embedding

find_embedding::embeddingembedding(embedding_problem_t &e_p, map<int, vector<int>> &fixed_chains, map<int, vector<int>> &initial_chains)

constructor for an initial embedding: accepts fixed and initial chains, populates the embedding based on them, and attempts to link adjacent chains together.

embedding<embedding_problem_t> &find_embedding::embeddingoperator=(const embedding<embedding_problem_t> &other)

copy the data from other.var_embedding into this.var_embedding

const chain &find_embedding::embeddingget_chain(int v) const

Get the variables in a chain.

int find_embedding::embeddingchainsize(int v) const

Get the size of a chain.

int find_embedding::embeddingweight(int q) const

Get the weight of a qubit.

int find_embedding::embeddingmax_weight() const

Get the maximum of all qubit weights.

int find_embedding::embeddingmax_weight(const int start, const int stop) const

Get the maximum of all qubit weights in a range.

bool find_embedding::embeddinghas_qubit(const int v, const int q) const

Check if variable v is includes qubit q in its chain.

void find_embedding::embeddingset_chain(const int u, const vector<int> &incoming)

Assign a chain for variable u.

void find_embedding::embeddingfix_chain(const int u, const vector<int> &incoming)

Permanently assign a chain for variable u.

NOTE: This must be done before any chain is assigned to u.

bool find_embedding::embeddingoperator==(const embedding &other) const

check if this and other have the same chains (up to qubit containment per chain; linking and parent information is not checked)

void find_embedding::embeddingconstruct_chain(const int u, const int q, const vector<vector<int>> &parents)

construct the chain for u, rooted at q, with a vector of parent info, where for each neibor v of u, following q -> parents[v][q] -> parents[v][parents[v][q]] …

terminates in the chain for v

void find_embedding::embeddingflip_back(int u, const int target_chainsize)

distribute path segments to the neighboring chains path segments are the qubits that are ONLY used to join link_qubit[u][v] to link_qubit[u][u] and aren’t used for any other variable

• if the target chainsize is zero, dump the entire segment into the neighbor
• if the target chainsize is k, stop when the neighbor’s size reaches k

void find_embedding::embeddingtear_out(int u)

short tearout procedure blank out the chain, its linking qubits, and account for the qubits being freed

void find_embedding::embeddingsteal_all(int u)

grow the chain for u, stealing all available qubits from neighboring variables

int find_embedding::embeddingstatistics(vector<int> &stats) const

compute statistics for this embedding and return 1 if no chains are overlapping when no chains are overlapping, populate stats with a chainlength histogram chains do overlap, populate stats with a qubit overfill histogram a histogram, in this case, is a vector of size (maximum attained value+1) where stats[i] is either the number of qubits contained in i+2 chains or the number of chains with size i

bool find_embedding::embeddinglinked() const

check if the embedding is fully linked that is, if each pair of adjacent variables is known to correspond to a pair of adjacent qubits

bool find_embedding::embeddinglinked(int u) const

check if a single variable is linked with all adjacent variables.

void find_embedding::embeddingprint() const

print out this embedding to a level of detail that is useful for debugging purposes TODO describe the output format.

void find_embedding::embeddinglong_diagnostic(char *current_state)

run a long diagnostic, and if debugging is enabled, record current_state so that the error message has a little more context.

if an error is found, throw -1

void find_embedding::embeddingrun_long_diagnostic(char *current_state) const

run a long diagnostic to verify the integrity of this datastructure.

the guts of this function are its documentation, because this function only exists for debugging purposes

Private Functions

bool find_embedding::embeddinglinkup(int u, int v)

This method attempts to find the linking qubits for a pair of adjacent variables, and returns true/false on success/failure in finding that pair.

Private Members

embedding_problem_t &find_embedding::embeddingep

int find_embedding::embeddingnum_qubits

int find_embedding::embeddingnum_reserved

int find_embedding::embeddingnum_vars

int find_embedding::embeddingnum_fixed

vector<chain> find_embedding::embeddingvar_embedding

this is where we store chains see chain.hpp for how

vector<int> find_embedding::embeddingqub_weight

weights, that is, the number of non-fixed chains that use each qubit this is used in pathfinder clases to determine non-overlapped, or or least-overlapped paths through the qubit graph