@ny23456 , I think it depends. DS had taken most of the “undergrad” theoretical CS courses already, and since it’s his area of interest, would have take the “grad” courses anyway.
MS/BS (or MA/BA) approvals in some majors are very formal. DS reports that in CS it was a relatively informal process.
Candidates must satisfy the Yale College requirements for the B.S. degree in Computer Science.
In fulfilling these requirements, students must complete eight graduate courses from the approved list, up to two of which may, with the permission of the director of undergraduate studies and the director of graduate studies, also be applied toward completion of the B.S. degree. Since the student will be taking CPSC 490 Special Projects, at most one of these courses may be CPSC 690, 691, or 692 Independent Project.
Graduate work must not be entirely concentrated in the final two terms of study, and students must take at least six term courses outside computer science during their last four terms at Yale and at least two undergraduate courses during their last two terms.
Students must apply for admission to this program through the director of undergraduate studies no later than the last day of their fifth term in Yale College. Applicants must have achieved A, A–, or Honors grades in at least two-thirds of their course credits as well as in at least three-fourths of all course credits that directly relate to Computer Science. See the official regulations for what goes into an application proposal. Application proposals should be submitted to the DUS by email.