7. Let 5-{0 0 0 ]} E contains all size-3 columns of O's and l's (23 = 8 columns). A string we 5* gives three rows of O's and l's. 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, 8 ! 1) B, but i ! 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 5-{0 0 0 ]} E contains all size-3 columns of O's and l's (23 = 8 columns). A string we 5* gives three rows of O's and l's. 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, 8 ! 1) B, but i ! 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).)