If the proteins are not related, the events that the two aligned amino acids are the i {\displaystyle i} th and j {\displaystyle j} th amino acids must be independent. The probabilities of these events are f ( i ) {\displaystyle f(i)} and f ( j ) {\displaystyle f(j)} , which means the probability of the alignment is f ( i ) f ( j ) {\displaystyle f(i)f(j)} , the denominator of the logarithm. Thus, the logarithm in the equation results in a positive entry if the alignment is more likely due to point accepted mutations, and a negative entry if the alignment is more likely due to chance.