Knowledge acquisition is when we ask experts questions, and put the answers into the computer system. Since this is a very time-consuming task, it is desirable to minimize the effort of an expert.
As a crude estimate for this effort, we can take a number of binary (yes-no) questions that we ask. The procedure that minimizes this number is binary search.
This approach does not take into account that people often feel more comfortable answering "yes" than answering "no". So, to make our estimates more realistic, we will take into consideration that for a negative answer the effort is bigger.
This paper describes a procedure that minimizes the effort of an expert. We also estimate the effort of this "optimal" search procedure.