// Can pass root as an argument, but will not affect performance much
double DESPOT::WEU(VNode* vnode, double xi) {
VNode* root = vnode;
while (root->parent() != NULL) {
root = root->parent()->parent();
}
return Gap(vnode) - xi * vnode->Weight() * Gap(root);
}
VNode* DESPOT::FindBlocker(VNode* vnode) {
VNode* cur = vnode;
int count = 1;
while (cur != NULL) {
if (cur->utility_upper_bound - count * Globals::config.pruning_constant
<= cur->default_move().value) {
break;
}
count++;
if (cur->parent() == NULL) {
cur = NULL;
} else {
cur = cur->parent()->parent();
}
}
return cur;
}
void DESPOT::ExploitBlockers(VNode* vnode) {
if (Globals::config.pruning_constant <= 0) {
return;
}
VNode* cur = vnode;
while (cur != NULL) {
VNode* blocker = FindBlocker(cur);
if (blocker != NULL) {
if (cur->parent() == NULL || blocker == cur) {
double value = cur->default_move().value;
cur->lower_bound(value);
cur->upper_bound(value);
cur->utility_upper_bound = value;
} else {
const map<OBS_TYPE, VNode*>& siblings =
cur->parent()->children();
for (map<OBS_TYPE, VNode*>::const_iterator it = siblings.begin();
it != siblings.end(); it++) {
VNode* node = it->second;
double value = node->default_move().value;
node->lower_bound(value);
node->upper_bound(value);
node->utility_upper_bound = value;
}
}
Backup(cur);
if (cur->parent() == NULL) {
cur = NULL;
} else {
cur = cur->parent()->parent();
}
} else {
break;
}
}
}
