Architecture students discovered Monday morning that some Pepsi posters, which were being used to advertise a lecture, had been smeared by some women's liberationists or their sympathizers. The perpetrators of the deed were objecting to sexist advertising of products and of this lecture. Warren Chalk, a psychologist, will speak all the same Thursday night to Planning students. Because of this incident, and a certain amount of thievery, the Architecture School will be locked up at night to prevent non-architecture students from using the building.