New Release - HUGIN 7.3
Today, March 29, 2010, we are releasing a new version of the HUGIN software
(v7.3). The main new feature of this release is the introduction of a new node
type called the "function" node type.
A function node represents a numerical value computed from the results of a
propagation in a network. A function node allows the user to define
mathematical expressions representing a value computed after a successful
propagation (or simulation) in a network. The function node can have continuous
nodes, discrete chance nodes, and utility nodes as parents. The expression is
defined using the Table Generator.
The development of the functionality concerning the function node type
(introduced in HUGIN 7.3) has been sponsored by Danish mortgage credit
institution Nykredit Realkredit (www.nykredit.dk).
HUGIN Graphical User Interface v7.3
The HUGIN Graphical User Interface has been improved with various new
features. This includes:
- A dialog for determining
the number of states of a hidden node has been introduced. The number of
states is determined by iterating over all state space sizes from a
minimum to a maximum value set by the user. The user can select from a
number of different scoring methods. For each iteration a parameter
estimation is performed and the user has the option to set the number of
states of the hidden node to the best scoring option.
- A dialog to perform feature
selection has been introduced. The feature selection is performed relative
to a target node. For each node represented in data, a score of the
correlation between the node and the selected target node is computed. The
result is a list of the nodes sorted according to the score.
- The Chow-Liu algorithm has been
included in the Learning Wizard. The Chow-Liu algorithm allows the user to
learn a tree structure over the discrete chance nodes represented in data.
The resulting tree is a maximum-likelihood estimate of the unknown
distribution generating the data (under the tree structure constraint).
- A tree-augmented naive
Bayes model (TAN) learning algorithm has been included in the Learning
Wizard. The TAN learning algorithm is based on the Chow-Liu algorithm. It
learns a tree structure over the attribute nodes of a TAN model given a
target node.
- The support for
Object-Oriented Networks (OONs) has been improved with new functionality
for navigating OONs in run-mode. This includes support for opening monitor
and policy windows of nodes inside an instance node and traversal of
instance nodes.
- Vector Quality PDF export
for network structure.
- The adaptation wizard now
supports the inspection of probability distributions for nodes not subject
to adaptation
- When loading a case from
file the probability of the evidence in the case is reported to the status
bar
- Other minor improvements.
Finally, efforts have been put into improving the performance of the HUGIN
Graphical User Interface.
HUGIN Decision Engine v7.3
The HUGIN Decision Engine has been extended with the following features:
- A new node type has been
introduced: The "function" node type. This node type is used to
express calculations to be performed using the results of inference or
simulation as input. However, function nodes are not involved in the
inference process itself, so evidence cannot be specified for function
nodes.
- Here is a list of changes
related to the introduction of function nodes:
- The category of
function nodes is "h_category_function", and the kind is
"h_kind_other" (this kind is also used for utility and instance
nodes).
- A real-valued
function is associated with each function node. This function is
specified using a model.
- The function
associated with a function node must only depend on the parents of the
node. The parents can be of any type of node (except instance nodes).
- The value of a
function node based on the results of inference is requested by the
"h_node_get_value" function.
- The value of a
function node based on the results of simulation is requested by the
"h_node_get_sampled_value" function.
- The
"h_domain_new_node", "h_node_clone", and
"h_node_delete" functions do not uncompile if a function node
is involved.
- The
"h_node_add_parent", "h_node_remove_parent", and
"h_node_switch_parent" functions do not uncompile if the child
node is a function node.
- The HKB format has
been updated to support networks with function nodes (but the old format
is still used for networks without function nodes).
- The NET language has
been extended: The new "function" keyword denotes the
definition of a function node, and "potential" specifications
are now also used to specify links and models for function nodes.
- The results of simulation
are now invalidated by (implicit as well as explicit) uncompile
operations.
- The new
"h_node_get_sampled_utility" function requests the
"sampled" utility of a utility node.
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