This assignment concerns the relational schema for a bookstore as shown in figure 1. create table CUSTOMER ( CID text primary key, NAME text, DOB date ); create table BOOK ( ISBN text primary key, TITLE text, AUTHOR text ); create table BUYS ( BID uuid primary key, CID text foreign key references CUSTOMER, ISBN text foreign key references BOOK, DATE timestamp, PRICE float ); 2. Given R(A, B, C) and S(B, D), prove or disprove the following RA propositions. As- sume all columns have the same domain (e.g. strings). (a) TB,C(R) S=7B,C,D( RS). (b) If A + B holds for instances of R, then PA-B(TTA,C(R)) S = 7B,C(R) S. (c) If A + B holds for instances of R, then TA,B(R) NA,C(R) = R