hegerf/The_structure_of_spac… · Let WI and VV3 be the lines through P parallel to WI and w3. Let...
5
hegerf/The_structure_of_spac… · Let WI and VV3 be the lines through P parallel to WI and w3. Let PI e WI, PI + P, and let W2 be the line through PI parallel to w2. These lines