Implementation--
Terminal Node List and Entries
The Terminal Node List holds references to the current set of leaf nodes in the search tree. Each terminal node list entry is one reference to one of the leaf nodes. Entries are placed in the terminal node list as each node is added to the search tree. When a node in the search tree is selected for processing, its entry in the terminal node list is removed from the list. If the number of nodes in the terminal node list reaches 0 at the time that a choice of search tree nodes is made, all of the branches of the search tree have been pruned back to the root node and the goal cannot be reached. The number of nodes in the terminal node list for single program simulations will never exceed 1. The terminal node list is accessed at one other time: when the matching state checks are made for new nodes in the pruning system. Terminal node lists add no additional functionality over that of standard List functions. Terminal node list entries are Tree Nodes and add no additional functionality over that of the tree nodes.
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Andrew Tompkins
Beaverton, OR 97006
Last rev: 17 JUL 03
URL: http://home.comcast.net/~andytom/simplan.docs/control/term.node.list.html
