propositional logic

Question

Are these system specifications consistent? “Whenever the system software is being upgraded, users cannot access the file system. If users can access the file system, then they can save new files. If users cannot save new files, then the system software is not being upgraded.”

Answer 1

A: system s/w is being upgraded

B: user can access the file

C: can save new file

$(A\rightarrow\overline{B}) \wedge (B\rightarrow C)\wedge (\overline{C}\rightarrow \overline{A})$

for system to be consistence we need to search atleast one combination of A,B,C such that above premises implies true.

and one of the such combination are..

A	B	C
0	0	0/1