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Minor updates

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Anh-Dung Phan 2013-10-29 15:49:53 -07:00
parent 905f230b8f
commit e715ccbc98
3 changed files with 33 additions and 17 deletions
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5
src/smt/network_flow.h
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@ -47,7 +47,7 @@ namespace smt {
typedef dl_graph<Ext> graph; typedef dl_graph<Ext> graph;
typedef typename Ext::numeral numeral; typedef typename Ext::numeral numeral;
typedef typename Ext::fin_numeral fin_numeral; typedef typename Ext::fin_numeral fin_numeral;
graph & m_graph; graph m_graph;
// Denote supply/demand b_i on node i // Denote supply/demand b_i on node i
vector<fin_numeral> m_balances; vector<fin_numeral> m_balances;
@ -85,6 +85,9 @@ namespace smt {
// Initialize the network with a feasible spanning tree // Initialize the network with a feasible spanning tree
void initialize(); void initialize();
bool get_edge_id(dl_var source, dl_var target, edge_id & id);
void update_potentials(); void update_potentials();
void update_flows(); void update_flows();

41
src/smt/network_flow_def.h
View file

@ -34,8 +34,6 @@ namespace smt {
m_balances.resize(num_nodes); m_balances.resize(num_nodes);
m_potentials.resize(num_nodes); m_potentials.resize(num_nodes);
m_flows.resize(num_edges);
m_states.resize(num_edges);
m_upwards.resize(num_nodes); m_upwards.resize(num_nodes);
m_pred.resize(num_nodes); m_pred.resize(num_nodes);
@ -58,12 +56,15 @@ namespace smt {
m_final[root] = root - 1; m_final[root] = root - 1;
m_potentials[root] = numeral::zero(); m_potentials[root] = numeral::zero();
m_graph.init_var(root);
fin_numeral sum_supply = fin_numeral::zero(); fin_numeral sum_supply = fin_numeral::zero();
for (unsigned i = 0; i < m_balances.size(); ++i) { for (unsigned i = 0; i < m_balances.size(); ++i) {
sum_supply += m_balances[i]; sum_supply += m_balances[i];
} }
m_balances[root] = -sum_supply; m_balances[root] = -sum_supply;
m_flows.resize(num_nodes + num_edges);
m_states.resize(num_nodes + num_edges); m_states.resize(num_nodes + num_edges);
m_states.fill(NON_BASIS); m_states.fill(NON_BASIS);
@ -74,14 +75,25 @@ namespace smt {
m_depth[i] = 1; m_depth[i] = 1;
m_thread[i] = i + 1; m_thread[i] = i + 1;
m_final[i] = i; m_final[i] = i;
m_rev_thread[i] = (i == 0) ? root : i - 1; m_rev_thread[i + 1] = i;
m_states[num_edges + i] = BASIS; m_states[num_edges + i] = BASIS;
node src = m_upwards[i] ? i : root;
node tgt = m_upwards[i] ? root : i;
m_flows[num_edges + i] = m_upwards[i] ? m_balances[i] : -m_balances[i];
m_graph.enable_edge(m_graph.add_edge(src, tgt, numeral::one(), explanation()));
} }
TRACE("network_flow", tout << pp_vector("Predecessors", m_pred, true) << pp_vector("Threads", m_thread) TRACE("network_flow", tout << pp_vector("Predecessors", m_pred, true) << pp_vector("Threads", m_thread)
<< pp_vector("Reverse Threads", m_rev_thread) << pp_vector("Last Successors", m_final) << pp_vector("Depths", m_depth);); << pp_vector("Reverse Threads", m_rev_thread) << pp_vector("Last Successors", m_final) << pp_vector("Depths", m_depth););
} }
template<typename Ext>
bool network_flow<Ext>::get_edge_id(dl_var source, dl_var target, edge_id & id) {
// m_upwards decides which node is the real source
return m_upwards[source] ? m_graph.get_edge_id(source, target, id) : m_graph.get_edge_id(target, source, id);
}
template<typename Ext> template<typename Ext>
void network_flow<Ext>::update_potentials() { void network_flow<Ext>::update_potentials() {
TRACE("network_flow", tout << "update_potentials...\n";); TRACE("network_flow", tout << "update_potentials...\n";);
@ -105,13 +117,13 @@ namespace smt {
node source = m_graph.get_source(m_entering_edge); node source = m_graph.get_source(m_entering_edge);
for (unsigned u = source; u != m_join_node; u = m_pred[u]) { for (unsigned u = source; u != m_join_node; u = m_pred[u]) {
edge_id e_id; edge_id e_id;
m_graph.get_edge_id(u, m_pred[u], e_id); get_edge_id(u, m_pred[u], e_id);
m_flows[e_id] += m_upwards[u] ? -val : val; m_flows[e_id] += m_upwards[u] ? -val : val;
} }
node target = m_graph.get_target(m_entering_edge); node target = m_graph.get_target(m_entering_edge);
for (unsigned u = target; u != m_join_node; u = m_pred[u]) { for (unsigned u = target; u != m_join_node; u = m_pred[u]) {
edge_id e_id; edge_id e_id;
m_graph.get_edge_id(u, m_pred[u], e_id); get_edge_id(u, m_pred[u], e_id);
m_flows[e_id] += m_upwards[u] ? val : -val; m_flows[e_id] += m_upwards[u] ? val : -val;
} }
TRACE("network_flow", tout << pp_vector("Flows", m_flows, true);); TRACE("network_flow", tout << pp_vector("Flows", m_flows, true););
@ -159,6 +171,7 @@ namespace smt {
} }
// Found first common ancestor of source and target // Found first common ancestor of source and target
m_join_node = u; m_join_node = u;
TRACE("network_flow", tout << "Found join node " << m_join_node << std::endl;);
// FIXME: need to get truly infinite value // FIXME: need to get truly infinite value
numeral infty = numeral(INT_MAX); numeral infty = numeral(INT_MAX);
m_delta = infty; m_delta = infty;
@ -166,7 +179,7 @@ namespace smt {
// Send flows along the path from source to the ancestor // Send flows along the path from source to the ancestor
for (unsigned u = source; u != m_join_node; u = m_pred[u]) { for (unsigned u = source; u != m_join_node; u = m_pred[u]) {
edge_id e_id; edge_id e_id;
m_graph.get_edge_id(u, m_pred[u], e_id); get_edge_id(u, m_pred[u], e_id);
numeral d = m_upwards[u] ? m_flows[e_id] : infty; numeral d = m_upwards[u] ? m_flows[e_id] : infty;
if (d < m_delta) { if (d < m_delta) {
m_delta = d; m_delta = d;
@ -178,7 +191,7 @@ namespace smt {
// Send flows along the path from target to the ancestor // Send flows along the path from target to the ancestor
for (unsigned u = target; u != m_join_node; u = m_pred[u]) { for (unsigned u = target; u != m_join_node; u = m_pred[u]) {
edge_id e_id; edge_id e_id;
m_graph.get_edge_id(u, m_pred[u], e_id); get_edge_id(u, m_pred[u], e_id);
numeral d = m_upwards[u] ? infty : m_flows[e_id]; numeral d = m_upwards[u] ? infty : m_flows[e_id];
if (d <= m_delta) { if (d <= m_delta) {
m_delta = d; m_delta = d;
@ -188,8 +201,8 @@ namespace smt {
} }
if (m_delta < infty) { if (m_delta < infty) {
m_graph.get_edge_id(src, tgt, m_leaving_edge); get_edge_id(src, tgt, m_leaving_edge);
TRACE("network_flow", tout << "Found leaving edge" << m_leaving_edge << "between node " << src << " and node " << tgt << "...\n";); TRACE("network_flow", tout << "Found leaving edge " << m_leaving_edge << " between node " << src << " and node " << tgt << "...\n";);
return true; return true;
} }
TRACE("network_flow", tout << "Can't find a leaving edge... The problem is unbounded.\n";); TRACE("network_flow", tout << "Can't find a leaving edge... The problem is unbounded.\n";);
@ -232,8 +245,8 @@ namespace smt {
} }
node gamma = m_thread[m_final[src_in]]; node gamma = m_thread[m_final[src_in]];
last = m_pred[gamma] != 0 ? gamma : root; last = m_pred[gamma] != -1 ? gamma : root;
for (node u = src_in; u == last; u = m_pred[u]) { for (node u = src_in; u != last; u = m_pred[u]) {
m_final[u] = z; m_final[u] = z;
} }
@ -245,8 +258,8 @@ namespace smt {
gamma = m_thread[m_final[tgt_out]]; gamma = m_thread[m_final[tgt_out]];
// REVIEW: check f(u) is not in T_v // REVIEW: check f(u) is not in T_v
node delta = m_final[src_out] != m_final[tgt_out] ? m_final[src_out] : m_rev_thread[tgt_out]; node delta = m_final[src_out] != m_final[tgt_out] ? m_final[src_out] : m_rev_thread[tgt_out];
last = m_pred[gamma] != 0 ? gamma : root; last = m_pred[gamma] != -1 ? gamma : root;
for (node u = src_in; u == last; u = m_pred[u]) { for (node u = src_in; u != last; u = m_pred[u]) {
m_final[u] = delta; m_final[u] = delta;
} }
@ -281,7 +294,7 @@ namespace smt {
// Decrease depth of all children in the subtree // Decrease depth of all children in the subtree
++count; ++count;
int d = m_depth[u] - count; int d = m_depth[u] - count;
for (node v = m_thread[u]; v == m_final[u]; v = m_thread[v]) { for (node v = m_thread[u]; v != m_final[u]; v = m_thread[v]) {
m_depth[v] -= d; m_depth[v] -= d;
} }
} }