my $profile = {
optional => [qw( f_course f_month f_year )],
required => [qw( f_a, f_b )],
dependencies   => {
    # If f_course is entered, make f_month and f_year required
    # Or if f_month is entered, make f_course and f_year required
    # Or if f_year is entered, make f_course and f_month required
  },
};