Direct Proof

SOLVED:Give direct and indirect proofs of: (a) a \rightarrow b, c \rightarrow b, d \rightarrow(a \vee c), d \Rightarrow b. (b) (p \rightarrow q) \wedge(r \rightarrow s),(q \rightarrow t) \wedge(s \rightarrow u), \neg(t \wedge u), p \rightarrow r \Rightarrow \neg p . (c) p \rightarrow(q \rightarrow r), \neg s \vee p, q \Rightarrow s \rightarrow r . (d) p \rightarrow q_{1} q \rightarrow r_{1} \neg(p \wedge r), p \vee r \Rightarrow r (e) \neg q \cdot p \rightarrow q \cdot p \vee t \Rightarrow t

How to Write Indirect Proofs by Contradiction | Geometry | Study.com