# Deliberative and Conceptual Inference in Service Robots
## 6 Non-Monotonic Knowledge-Base Service
An instance of case (ii) is when the \(take\) behavior, which includes a \(see\) behavior, fails to find the object in its expected shelf. This failure prompts the execution of the daily-life inference cycle. Whenever the expectations of the robot are not met in the environment, the robot needs first to make a diagnosis inference and find a potential explanation for the failure; induce a decision dynamically as how to proceed and such decision becomes the goal for the induction and execution of a plan. The present model makes extensive use of diagnosis and decision-making and contrasts in this regard with models focus on planning mostly [34; 44; 63; 64; 65], as discussed in relation of the deliberative functions [33]. ## 8 Deliberative Inference

This inference strategy is illustrated with the supermarket scenario in Figure 1. This has the following elements:

1. The supermarket consists of a finite set of shelves \(S=\{s_{1},...s_{n}\}\) at their corresponding locations \(L=\{l_{1},...,l_{n}\}\), each having an arbitrary number of objects or entities \(O=\{o_{1},...,o_{n}\}\) of a particular designated class \(c_{i}\in C\), the set of classes; for instance, \(C=\{drinks,food,pred\}\);
2. The human client, who may require assistance;The robot, which has a number of conversational, task, and cognitive obligations;
4. A human supermarket assistant whose job is to bring the products from the supermarket's storage and place them on their corresponding shelves. The cognitive, conversational, and task obligations are as stated above. A typical command is _bring me a coke_, which is interpreted as \([\textit{acknowledge},\textit{grasp}(\textit{coke}),\textit{find}(\textit{user}), \textit{deliver}(\textit{coke},\textit{user})]\), where \(\textit{grasp}(\textit{coke})\) is the composite behavior \(\textit{kb\_get\_shelf\_of\_object}(\textit{object}_{i},\textit{shelf}_{j})\), \(\textit{move}(\textit{shelf}_{j})\), \(\textit{find}(\textit{object}_{i})\), and \(\textit{take}(\textit{object}_{i})\). In this scenario, the priority is to satisfy the customer, and a sensible strategy is to achieve the \(\textit{take}(\textit{object}_{i})\) action as soon as possible and complete the execution of the command, and use the idle time to carry on with the \(\textit{Pending\_Task}\). These two goals interact, and the robot may place some misplaced objects along the way if the actions deviate little from the main conversational obligation. If the sought object is placed at its right shelf, the command can be performed directly; otherwise, the robot must engaged in the daily-life inference cycle to find the object, take it, and deliver it to the customer. These conditions are handled by the behavior's manager of the behavior _take_, which, in turn, uses the behavior _see_, with its associated cognitive obligations. The arguments of the inference procedure are:

1. The current \(\textit{take}(\textit{object}_{i})\) behavior;
2. The list \(\textit{Previous\_Shelves}\) of shelves already inspected by the robot including the objects placed on them, which corresponds to the states of the shelves as arranged by the human assistant when the scenario was created, as discussed below in 8.1; this list is initially empty;
3. The set \(\textit{Objects\_Placed}\) of objects already put in their right locations by previous successful place actions performed by the robot in the current inference cycle; this set is initially empty. The inference cycle proceeds as follows:

1. Perform a diagnosis inference in relation to the actual observations already made by the robot; this inference renders the assumed actions made by the human assistant when he or she filled up the stands including the misplaced objects \(\textit{Misplaced}_{\textit{KB}}\);
2. Compute the \(\textit{Decision}\) in relation to the current goal, e.g., \(\textit{take}(\textit{object}_{i})\), and possibly other subordinated place actions in the current \(\textit{Pending\_Task}\);
3. Induce the plan consisting of the list of behaviors \(\textit{Plan}\) to achieved \(\textit{Decision}\);
4.