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start working on network flow

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2013-12-04 14:38:03 -08:00
parent d6f0c13f2a
commit a1a8aad09b
5 changed files with 77 additions and 80 deletions
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2
src/smt/network_flow.h
View file

@ -30,7 +30,7 @@ Notes:
#include"inf_rational.h"
#include"diff_logic.h"
#include"spanning_tree_def.h"
#include"spanning_tree.h"
namespace smt {

1
src/smt/network_flow_def.h
View file

@ -22,6 +22,7 @@ Notes:
#include"network_flow.h"
#include"uint_set.h"
#include"spanning_tree_def.h"
namespace smt {

31
src/smt/spanning_tree.h
View file

@ -27,44 +27,41 @@ namespace smt {
template<typename Ext>
class thread_spanning_tree : public spanning_tree_base, protected Ext {
protected:
typedef dl_var node;
typedef dl_edge<Ext> edge;
typedef dl_graph<Ext> graph;
typedef typename Ext::numeral numeral;
typedef typename Ext::fin_numeral fin_numeral;
// Store the parent of a node i in the spanning tree
svector<node> m_pred;
svector<node_id> m_pred;
// Store the number of edge on the path from node i to the root
svector<int> m_depth;
// Store the pointer from node i to the next node in depth-first search order
svector<node> m_thread;
svector<node_id> m_thread; // Store the pointer from node i to the next node in depth-first search order
// i |-> edge between (i, m_pred[i])
svector<edge_id> m_tree;
svector<edge_id> m_tree; // i |-> edge between (i, m_pred[i])
node m_root_t2;
node_id m_root_t2;
graph & m_graph;
void swap_order(node q, node v);
node find_rev_thread(node n) const;
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);
void swap_order(node_id q, node_id v);
node_id find_rev_thread(node_id n) const;
void fix_depth(node_id start, node_id after_end);
node_id get_final(int start);
bool is_preorder_traversal(node_id start, node_id end);
node_id get_common_ancestor(node_id u, node_id v);
bool is_forward_edge(edge_id e_id) const;
bool is_ancestor_of(node ancestor, node child);
bool is_ancestor_of(node_id ancestor, node_id child);
public:
thread_spanning_tree(graph & g);
virtual void initialize(svector<edge_id> const & tree);
void get_descendants(node start, svector<node> & descendants);
void get_descendants(node_id start, svector<node_id> & descendants);
virtual void update(edge_id enter_id, edge_id leave_id);
void get_path(node start, node end, svector<edge_id> & path, svector<bool> & against);
bool in_subtree_t2(node child);
void get_path(node_id start, node_id end, svector<edge_id> & path, svector<bool> & against);
bool in_subtree_t2(node_id child);
bool check_well_formed();
};

13
src/smt/spanning_tree_base.h
View file

@ -43,19 +43,18 @@ namespace smt {
}
class spanning_tree_base {
private:
typedef int node;
public:
typedef int node_id;
typedef int edge_id;
virtual void initialize(svector<edge_id> const & tree) = 0;
virtual void get_descendants(node start, svector<node> & descendants) = 0;
virtual void get_descendants(node_id start, svector<node_id> & descendants) = 0;
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 void get_path(node_id start, node_id end, svector<edge_id> & path, svector<bool> & against) = 0;
virtual bool in_subtree_t2(node_id child) = 0;
virtual bool check_well_formed() = 0;
};
}
#endif
#endif

110
src/smt/spanning_tree_def.h
View file

@ -37,7 +37,7 @@ namespace smt {
m_depth.resize(num_nodes);
m_thread.resize(num_nodes);
node root = num_nodes - 1;
node_id root = num_nodes - 1;
m_pred[root] = -1;
m_depth[root] = 0;
m_thread[root] = 0;
@ -56,7 +56,7 @@ namespace smt {
}
template<typename Ext>
typename thread_spanning_tree<Ext>::node thread_spanning_tree<Ext>::get_common_ancestor(node u, node v) {
typename thread_spanning_tree<Ext>::node_id thread_spanning_tree<Ext>::get_common_ancestor(node_id u, node_id v) {
while (u != v) {
if (m_depth[u] > m_depth[v])
u = m_pred[u];
@ -67,8 +67,8 @@ namespace smt {
}
template<typename Ext>
void thread_spanning_tree<Ext>::get_path(node start, node end, svector<edge_id> & path, svector<bool> & against) {
node join = get_common_ancestor(start, end);
void thread_spanning_tree<Ext>::get_path(node_id start, node_id end, svector<edge_id> & path, svector<bool> & against) {
node_id join = get_common_ancestor(start, end);
path.reset();
while (start != join) {
edge_id e_id = m_tree[start];
@ -86,17 +86,17 @@ namespace smt {
template<typename Ext>
bool thread_spanning_tree<Ext>::is_forward_edge(edge_id e_id) const {
node start = m_graph.get_source(e_id);
node end = m_graph.get_target(e_id);
node_id start = m_graph.get_source(e_id);
node_id end = m_graph.get_target(e_id);
SASSERT(m_pred[start] == end || m_pred[end] == start);
return m_pred[start] == end;
}
template<typename Ext>
void thread_spanning_tree<Ext>::get_descendants(node start, svector<node> & descendants) {
void thread_spanning_tree<Ext>::get_descendants(node_id start, svector<node_id> & descendants) {
descendants.reset();
descendants.push_back(start);
node u = m_thread[start];
node_id u = m_thread[start];
while (m_depth[u] > m_depth[start]) {
descendants.push_back(u);
u = m_thread[u];
@ -105,7 +105,7 @@ namespace smt {
}
template<typename Ext>
bool thread_spanning_tree<Ext>::in_subtree_t2(node child) {
bool thread_spanning_tree<Ext>::in_subtree_t2(node_id child) {
if (m_depth[child] < m_depth[m_root_t2]) {
return false;
}
@ -113,8 +113,8 @@ namespace smt {
}
template<typename Ext>
bool thread_spanning_tree<Ext>::is_ancestor_of(node ancestor, node child) {
for (node n = child; n != -1; n = m_pred[n]) {
bool thread_spanning_tree<Ext>::is_ancestor_of(node_id ancestor, node_id child) {
for (node_id n = child; n != -1; n = m_pred[n]) {
if (n == ancestor) {
return true;
}
@ -140,10 +140,10 @@ namespace smt {
*/
template<typename Ext>
void thread_spanning_tree<Ext>::update(edge_id enter_id, edge_id leave_id) {
node p = m_graph.get_source(enter_id);
node q = m_graph.get_target(enter_id);
node u = m_graph.get_source(leave_id);
node v = m_graph.get_target(leave_id);
node_id p = m_graph.get_source(enter_id);
node_id q = m_graph.get_target(enter_id);
node_id u = m_graph.get_source(leave_id);
node_id v = m_graph.get_target(leave_id);
if (m_pred[u] == v) {
std::swap(u, v);
@ -165,11 +165,11 @@ namespace smt {
// 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];
node_id f_p = get_final(p);
node_id f_v = get_final(v);
node_id alpha = find_rev_thread(v);
node_id beta = m_thread[f_v];
node_id gamma = m_thread[f_p];
if (v != gamma) {
m_thread[alpha] = beta;
@ -177,11 +177,11 @@ namespace smt {
m_thread[f_v] = gamma;
}
node old_pred = m_pred[q];
node_id old_pred = m_pred[q];
// Update stem nodes from q to v
if (q != v) {
for (node n = q; n != v; ) {
SASSERT(old_pred != u); // the last processed node is v
for (node_id n = q; n != v; ) {
SASSERT(old_pred != u); // the last processed node_id is v
SASSERT(-1 != m_pred[old_pred]);
int next_old_pred = m_pred[old_pred];
swap_order(n, old_pred);
@ -195,7 +195,7 @@ namespace smt {
m_tree[q] = enter_id;
m_root_t2 = q;
node after_final_q = (v == gamma) ? beta : gamma;
node_id after_final_q = (v == gamma) ? beta : gamma;
fix_depth(q, after_final_q);
SASSERT(!in_subtree_t2(p));
@ -226,15 +226,15 @@ namespace smt {
*/
template<typename Ext>
void thread_spanning_tree<Ext>::swap_order(node q, node v) {
void thread_spanning_tree<Ext>::swap_order(node_id q, node_id 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);
node_id prev = find_rev_thread(v);
node_id f_q = get_final(q);
node_id f_v = get_final(v);
node_id next = m_thread[f_v];
node_id alpha = find_rev_thread(q);
if (f_q == f_v) {
SASSERT(f_q != v && alpha != next);
@ -243,7 +243,7 @@ namespace smt {
f_q = alpha;
}
else {
node beta = m_thread[f_q];
node_id beta = m_thread[f_q];
SASSERT(f_q != v && alpha != beta);
m_thread[f_q] = v;
m_thread[alpha] = beta;
@ -262,13 +262,13 @@ namespace smt {
Spanning tree of m_graph + root is represented using:
svector<edge_state> m_states; edge_id |-> edge_state
svector<node> m_pred; node |-> node
svector<int> m_depth; node |-> int
svector<node> m_thread; node |-> node
svector<node_id> m_pred; node_id |-> node
svector<int> m_depth; node_id |-> int
svector<node_id> m_thread; node_id |-> node
Tree is determined by m_pred:
- m_pred[root] == -1
- m_pred[n] = m != n for each node n, acyclic until reaching root.
- m_pred[n] = m != n for each node_id n, acyclic until reaching root.
- m_depth[m_pred[n]] + 1 == m_depth[n] for each n != root
m_thread is a linked list traversing all nodes.
@ -278,13 +278,13 @@ namespace smt {
*/
template<typename Ext>
bool thread_spanning_tree<Ext>::check_well_formed() {
node root = m_pred.size()-1;
node_id root = m_pred.size()-1;
// Check that m_thread traverses each node.
// This gets checked using union-find as well.
svector<bool> found(m_thread.size(), false);
found[root] = true;
for (node x = m_thread[root]; x != root; x = m_thread[x]) {
for (node_id x = m_thread[root]; x != root; x = m_thread[x]) {
SASSERT(x != m_thread[x]);
found[x] = true;
}
@ -295,12 +295,12 @@ namespace smt {
// m_pred is acyclic, and points to root.
SASSERT(m_pred[root] == -1);
SASSERT(m_depth[root] == 0);
for (node i = 0; i < root; ++i) {
for (node_id i = 0; i < root; ++i) {
SASSERT(m_depth[m_pred[i]] < m_depth[i]);
}
// m_depth[x] denotes distance from x to the root node
for (node x = m_thread[root]; x != root; x = m_thread[x]) {
for (node_id x = m_thread[root]; x != root; x = m_thread[x]) {
SASSERT(m_depth[x] > 0);
SASSERT(m_depth[x] == m_depth[m_pred[x]] + 1);
}
@ -309,8 +309,8 @@ namespace smt {
// Union-find structure
svector<int> roots(m_pred.size(), -1);
for (node x = m_thread[root]; x != root; x = m_thread[x]) {
node y = m_pred[x];
for (node_id x = m_thread[root]; x != root; x = m_thread[x]) {
node_id y = m_pred[x];
// We are now going to check the edge between x and y
SASSERT(find(roots, x) != find(roots, y));
merge(roots, x, y);
@ -322,8 +322,8 @@ namespace smt {
}
for (unsigned i = 0; i < m_tree.size(); ++i) {
node src = m_graph.get_source(m_tree[i]);
node tgt = m_graph.get_target(m_tree[i]);
node_id src = m_graph.get_source(m_tree[i]);
node_id tgt = m_graph.get_target(m_tree[i]);
SASSERT(m_pred[src] == tgt || m_pred[tgt] == src);
}
@ -358,11 +358,11 @@ namespace smt {
}
/**
\brief find node that points to 'n' in m_thread
\brief find node_id that points to 'n' in m_thread
*/
template<typename Ext>
typename thread_spanning_tree<Ext>::node thread_spanning_tree<Ext>::find_rev_thread(node n) const {
node ancestor = m_pred[n];
typename thread_spanning_tree<Ext>::node_id thread_spanning_tree<Ext>::find_rev_thread(node_id n) const {
node_id ancestor = m_pred[n];
SASSERT(ancestor != -1);
while (m_thread[ancestor] != n) {
ancestor = m_thread[ancestor];
@ -371,7 +371,7 @@ namespace smt {
}
template<typename Ext>
void thread_spanning_tree<Ext>::fix_depth(node start, node after_end) {
void thread_spanning_tree<Ext>::fix_depth(node_id start, node_id after_end) {
while (start != after_end) {
SASSERT(m_pred[start] != -1);
m_depth[start] = m_depth[m_pred[start]]+1;
@ -380,7 +380,7 @@ namespace smt {
}
template<typename Ext>
typename thread_spanning_tree<Ext>::node thread_spanning_tree<Ext>::get_final(int start) {
typename thread_spanning_tree<Ext>::node_id thread_spanning_tree<Ext>::get_final(int start) {
int n = start;
while (m_depth[m_thread[n]] > m_depth[start]) {
n = m_thread[n];
@ -389,11 +389,11 @@ namespace smt {
}
template<typename Ext>
bool thread_spanning_tree<Ext>::is_preorder_traversal(node start, node end) {
bool thread_spanning_tree<Ext>::is_preorder_traversal(node_id start, node_id end) {
// get children of start
uint_set children;
children.insert(start);
node root = m_pred.size()-1;
node_id root = m_pred.size()-1;
for (int i = 0; i < root; ++i) {
for (int j = 0; j < root; ++j) {
if (children.contains(m_pred[j])) {
@ -434,7 +434,7 @@ namespace smt {
m_tree_graph->add_edge(e.get_source(), e.get_target(), e.get_weight(), explanation());
}
node root = num_nodes - 1;
node_id root = num_nodes - 1;
m_tree_graph->bfs_undirected(root, m_pred, m_depth);
m_tree_graph->dfs_undirected(root, m_thread);
}
@ -459,7 +459,7 @@ namespace smt {
edge const & e = es[enter_id];
m_tree_graph->add_edge(e.get_source(), e.get_target(), e.get_weight(), explanation());
node root = num_nodes - 1;
node_id root = num_nodes - 1;
m_tree_graph->bfs_undirected(root, m_pred, m_depth);
m_tree_graph->dfs_undirected(root, m_thread);
@ -479,11 +479,11 @@ namespace smt {
}
}
node p = m_graph.get_source(enter_id);
node q = m_graph.get_target(enter_id);
node_id p = m_graph.get_source(enter_id);
node_id q = m_graph.get_target(enter_id);
m_root_t2 = p == m_pred[q] ? q : p;
}
}
#endif
#endif