Cost estimation device, method and program for action model

A cost estimation method for an action model for estimating a cost related to an action for each of a plurality of sides indicating the action between a plurality of vertices indicating a state in the action model using a graph, the cost estimation method comprising:

• a process of acquiring graph data including at least information indicating a structure of the graph and a reward set for the plurality of vertices of the graph;
• a process of acquiring action data including a plurality of action trajectories in the graph;
• a process of expressing the cost using a parameter, and estimating the parameter using a gradient method related to a likelihood function on a basis of the graph data and the action data;
• and
• a process of outputting the estimated parameter as an estimated value of the cost.

A non-transitory tangible computer-readable storage medium storing a program for causing a hardware processor included in a cost estimation device for estimating a cost related to an action for each of a plurality of sides indicating the action between a plurality of vertices indicating a state in the action model using a graph,

• acquiring graph data including at least information indicating a structure of the graph and a reward set for the plurality of vertices of the graph;
• acquiring action data including a plurality of action trajectories in the graph;
• expressing the cost using a parameter and estimating the parameter using a gradient method related to a likelihood function on a basis of the graph data and the action data;
• and
• outputting the estimated parameter as an estimated value of the cost.