7. Let 2 = [, {8, [] -- [1]} contains all size-3 columns of O's and ls (23 8 columns). A string we * gives three rows of Os and ls. Consider each row to be a binary number and let = B = {w E *| the bottom row of w is the sum of the top two rows}. For example, but 9). & B. Show that B is regular. (You may find it easier to work with BR. In such case, you may assume the result claimed in 6(a).) 7. Let 2 = [, {8, [] -- [1]} contains all size-3 columns of O's and ls (23 8 columns). A string we * gives three rows of Os and ls. Consider each row to be a binary number and let = B = {w E *| the bottom row of w is the sum of the top two rows}. For example, but 9). & B. Show that B is regular. (You may find it easier to work with BR. In such case, you may assume the result claimed in 6(a).)