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Fix a few issues related to thread spanning tree

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This commit is contained in:
Anh-Dung Phan 2013-11-15 17:17:20 -08:00
parent 761c95129b
commit af8da013b5
5 changed files with 90 additions and 92 deletions
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2
src/smt/network_flow.h
View file

@ -244,7 +244,7 @@ namespace smt {
};
graph m_graph;
thread_spanning_tree<Ext> m_tree;
spanning_tree_base * m_tree;
// Denote supply/demand b_i on node i
vector<fin_numeral> m_balances;

20
src/smt/network_flow_def.h
View file

@ -27,8 +27,7 @@ namespace smt {
template<typename Ext>
network_flow<Ext>::network_flow(graph & g, vector<fin_numeral> const & balances) :
m_balances(balances),
m_tree(m_graph) {
m_balances(balances) {
// Network flow graph has the edges in the reversed order compared to constraint graph
// We only take enabled edges from the original graph
for (unsigned i = 0; i < g.get_num_nodes(); ++i) {
@ -42,6 +41,7 @@ namespace smt {
}
}
m_step = 0;
m_tree = alloc(thread_spanning_tree<Ext>, m_graph);
}
template<typename Ext>
@ -82,7 +82,7 @@ namespace smt {
tree.push_back(m_graph.add_edge(src, tgt, numeral::one(), explanation()));
}
m_tree.initialize(tree);
m_tree->initialize(tree);
TRACE("network_flow", {
tout << pp_vector("Potentials", m_potentials, true) << pp_vector("Flows", m_flows);
@ -96,14 +96,14 @@ namespace smt {
node src = m_graph.get_source(m_enter_id);
node tgt = m_graph.get_target(m_enter_id);
numeral cost = m_potentials[src] - m_potentials[tgt] - m_graph.get_weight(m_enter_id);
numeral change = m_tree.in_subtree_t2(tgt) ? cost : -cost;
numeral change = m_tree->in_subtree_t2(tgt) ? cost : -cost;
node start = m_graph.get_source(m_leave_id);
if (!m_tree.in_subtree_t2(start)) {
if (!m_tree->in_subtree_t2(start)) {
start = m_graph.get_target(m_leave_id);;
}
TRACE("network_flow", tout << "update_potentials of T_" << start << " with change = " << change << "...\n";);
svector<node> descendants;
m_tree.get_descendants(start, descendants);
m_tree->get_descendants(start, descendants);
SASSERT(descendants.size() >= 1);
for (unsigned i = 0; i < descendants.size(); ++i) {
node u = descendants[i];
@ -120,7 +120,7 @@ namespace smt {
node tgt = m_graph.get_target(m_enter_id);
svector<edge_id> path;
svector<bool> against;
m_tree.get_path(src, tgt, path, against);
m_tree->get_path(src, tgt, path, against);
SASSERT(path.size() >= 1);
for (unsigned i = 0; i < path.size(); ++i) {
edge_id e_id = path[i];
@ -138,7 +138,7 @@ namespace smt {
edge_id leave_id;
svector<edge_id> path;
svector<bool> against;
m_tree.get_path(src, tgt, path, against);
m_tree->get_path(src, tgt, path, against);
SASSERT(path.size() >= 1);
for (unsigned i = 0; i < path.size(); ++i) {
edge_id e_id = path[i];
@ -164,7 +164,7 @@ namespace smt {
template<typename Ext>
void network_flow<Ext>::update_spanning_tree() {
m_tree.update(m_enter_id, m_leave_id);
m_tree->update(m_enter_id, m_leave_id);
}
// FIXME: should declare pivot as a pivot_rule_impl and refactor
@ -240,7 +240,7 @@ namespace smt {
template<typename Ext>
bool network_flow<Ext>::check_well_formed() {
SASSERT(m_tree.check_well_formed());
SASSERT(m_tree->check_well_formed());
SASSERT(!m_delta || !(*m_delta).is_neg());
// m_flows are zero on non-basic edges

2
src/smt/spanning_tree.h
View file

@ -49,7 +49,7 @@ namespace smt {
void swap_order(node q, node v);
node find_rev_thread(node n) const;
void fix_depth(node start, node end);
void fix_depth(node start, node after_end);
node get_final(int start);
bool is_preorder_traversal(node start, node end);
node get_common_ancestor(node u, node v);

12
src/smt/spanning_tree_base.h
View file

@ -47,14 +47,14 @@ namespace smt {
typedef int node;
public:
virtual void initialize(svector<edge_id> const & tree) {};
virtual void get_descendants(node start, svector<node> & descendants) {};
virtual void initialize(svector<edge_id> const & tree) = 0;
virtual void get_descendants(node start, svector<node> & descendants) = 0;
virtual void update(edge_id enter_id, edge_id leave_id) {};
virtual void get_path(node start, node end, svector<edge_id> & path, svector<bool> & against) {};
virtual bool in_subtree_t2(node child) {UNREACHABLE(); return false;};
virtual void update(edge_id enter_id, edge_id leave_id) = 0;
virtual void get_path(node start, node end, svector<edge_id> & path, svector<bool> & against) = 0;
virtual bool in_subtree_t2(node child) = 0;
virtual bool check_well_formed() {UNREACHABLE(); return false;};
virtual bool check_well_formed() = 0;
};
}

146
src/smt/spanning_tree_def.h
View file

@ -162,11 +162,26 @@ namespace smt {
tout << u << ", " << v << ") leaves\n";
});
// Old threads: alpha -> v -*-> f(v) -> beta | p -*-> f(p) -> gamma
// New threads: alpha -> beta | p -*-> f(p) -> v -*-> f(v) -> gamma
node f_p = get_final(p);
node f_v = get_final(v);
node alpha = find_rev_thread(v);
node beta = m_thread[f_v];
node gamma = m_thread[f_p];
if (v != gamma) {
m_thread[alpha] = beta;
m_thread[f_p] = v;
m_thread[f_v] = gamma;
}
node old_pred = m_pred[q];
// Update stem nodes from q to v
if (q != v) {
for (node n = q; n != u; ) {
SASSERT(old_pred != u || n == v); // the last processed node is v
for (node n = q; n != v; ) {
SASSERT(old_pred != u); // the last processed node is v
SASSERT(-1 != m_pred[old_pred]);
int next_old_pred = m_pred[old_pred];
swap_order(n, old_pred);
@ -175,34 +190,18 @@ namespace smt {
old_pred = next_old_pred;
}
}
// Old threads: alpha -> q -*-> f(q) -> beta | p -*-> f(p) -> gamma
// New threads: alpha -> beta | p -*-> f(p) -> q -*-> f(q) -> gamma
node f_p = get_final(p);
node f_q = get_final(q);
node alpha = find_rev_thread(q);
node beta = m_thread[f_q];
node gamma = m_thread[f_p];
if (q != gamma) {
m_thread[alpha] = beta;
m_thread[f_p] = q;
m_thread[f_q] = gamma;
}
m_pred[q] = p;
m_tree[q] = enter_id;
m_root_t2 = q;
node after_final_q = (v == gamma) ? beta : gamma;
fix_depth(q, after_final_q);
SASSERT(!in_subtree_t2(p));
SASSERT(in_subtree_t2(q));
SASSERT(!in_subtree_t2(u));
SASSERT(in_subtree_t2(v));
// Update the depth.
fix_depth(q, get_final(q));
TRACE("network_flow", {
tout << pp_vector("Predecessors", m_pred, true) << pp_vector("Threads", m_thread);
@ -210,6 +209,53 @@ namespace smt {
});
}
/**
swap v and q in tree.
- fixup m_thread
- fixup m_pred
Case 1: final(q) == final(v)
-------
Old thread: prev -> v -*-> alpha -> q -*-> final(q) -> next
New thread: prev -> q -*-> final(q) -> v -*-> alpha -> next
Case 2: final(q) != final(v)
-------
Old thread: prev -> v -*-> alpha -> q -*-> final(q) -> beta -*-> final(v) -> next
New thread: prev -> q -*-> final(q) -> v -*-> alpha -> beta -*-> final(v) -> next
*/
template<typename Ext>
void thread_spanning_tree<Ext>::swap_order(node q, node v) {
SASSERT(q != v);
SASSERT(m_pred[q] == v);
SASSERT(is_preorder_traversal(v, get_final(v)));
node prev = find_rev_thread(v);
node f_q = get_final(q);
node f_v = get_final(v);
node next = m_thread[f_v];
node alpha = find_rev_thread(q);
if (f_q == f_v) {
SASSERT(f_q != v && alpha != next);
m_thread[f_q] = v;
m_thread[alpha] = next;
f_q = alpha;
}
else {
node beta = m_thread[f_q];
SASSERT(f_q != v && alpha != beta);
m_thread[f_q] = v;
m_thread[alpha] = beta;
f_q = f_v;
}
SASSERT(prev != q);
m_thread[prev] = q;
m_pred[v] = q;
// Notes: f_q has to be used since m_depth hasn't been updated yet.
SASSERT(is_preorder_traversal(q, f_q));
}
/**
\brief Check invariants of main data-structures.
@ -311,53 +357,6 @@ namespace smt {
roots[y] = x;
}
/**
swap v and q in tree.
- fixup m_thread
- fixup m_pred
Case 1: final(q) == final(v)
-------
Old thread: prev -> v -*-> alpha -> q -*-> final(q) -> next
New thread: prev -> q -*-> final(q) -> v -*-> alpha -> next
Case 2: final(q) != final(v)
-------
Old thread: prev -> v -*-> alpha -> q -*-> final(q) -> beta -*-> final(v) -> next
New thread: prev -> q -*-> final(q) -> v -*-> alpha -> beta -*-> final(v) -> next
*/
template<typename Ext>
void thread_spanning_tree<Ext>::swap_order(node q, node v) {
SASSERT(q != v);
SASSERT(m_pred[q] == v);
SASSERT(is_preorder_traversal(v, get_final(v)));
node prev = find_rev_thread(v);
node f_q = get_final(q);
node f_v = get_final(v);
node next = m_thread[f_v];
node alpha = find_rev_thread(q);
if (f_q == f_v) {
SASSERT(f_q != v && alpha != next);
m_thread[f_q] = v;
m_thread[alpha] = next;
f_q = alpha;
}
else {
node beta = m_thread[f_q];
SASSERT(f_q != v && alpha != beta);
m_thread[f_q] = v;
m_thread[alpha] = beta;
f_q = f_v;
}
SASSERT(prev != q);
m_thread[prev] = q;
m_pred[v] = q;
// Notes: f_q has to be used since m_depth hasn't been updated yet.
SASSERT(is_preorder_traversal(q, f_q));
}
/**
\brief find node that points to 'n' in m_thread
*/
@ -372,12 +371,11 @@ namespace smt {
}
template<typename Ext>
void thread_spanning_tree<Ext>::fix_depth(node start, node end) {
SASSERT(m_pred[start] != -1);
m_depth[start] = m_depth[m_pred[start]]+1;
while (start != end) {
start = m_thread[start];
void thread_spanning_tree<Ext>::fix_depth(node start, node after_end) {
while (start != after_end) {
SASSERT(m_pred[start] != -1);
m_depth[start] = m_depth[m_pred[start]]+1;
start = m_thread[start];
}
}