A slot-filling task (Figure 1) is most simple task of dialogue system. Typical domain of this task are telephone shopping, on-line banking, on-line trade, etc. The user has his/her purpose and knows almost all information in order to achieve the task. Most subdialogue of this task are devoted to filling the value at the slots (Figure 2) .
Fig. 2: Structure of slot-filling task
An example dialogue taken from telephone shopping is shown in Figure 3.
Fig. 3: Example dialogue of slot-filling task (telephone shopping)
Back-end application of this task is slot-filler. Each slot has slot name and may have the constraint to the value. The task is completed when all the necessary slot are filled by appropriate value.