for bcnf when were splitting the tables into 2. how do we know what FDs we use for each table? do we get it from what inside of the split tables? for example , in our excercise 3  in our first step of BCNF we split the table into R1 and R2. R1(faculty,phone,room} and R2{quarter,course,section_number,office_hours,faculty} so for r1 the FDs are all the FDs that have to do with whats inside of  R1(faculty,phone,room} ,  so 

{faculty} ⟶ {phone, room}

{room} ⟶ {faculty, phone}

{phone} ⟶ {faculty, room}

and  R2{quarter,course,section_number,office_hours,faculty}

{faculty, quarter} ⟶ {office_hours}

{course,quarter,section_number}--->{faculty}

so basically , all the FDs that have something in common with whats inside of the spit table? or is there another way of getting the FDs.