Note that the only way in which clu

Note that the only way in which clue 7 could be entered in the chart was to introduce symbols such as X and Y to represent people who have not yet been identified.(This is similar to the technique algebra in which letters are used to represent unknown number quantities.) In Figure 1.8, Mr. X represents Georgette’s husband and Y represents the name of Mr. Bennington’s wife, which is also the name of Mr.X’s horse.