>I am confused about how to create a sharpe file and how to execute it. 
>I think I know how to write a code but I didn't find instructions about the file. 

See the instruction for executing sharpe in the class webpage at https://people.cs.vt.edu/~irchen/5214/#software

>I'm still having trouble with creating the sharpe file. I'm currently under the usr/local/sharpe, but when I try to create a sharpe file by "touch hw.sh", it says "touch: hw.sh cannot create".


In the UNIX system, you would create your sharpe file in your home directory by using an editor like vi. First at the command prompt, type in "cd" and you will be back to your home directory. Then type "vi hw.sh" to edit a file named "hw.sh". Of course you need to fill in the content with sharpe program lines (like the ones covered in class) and then save the file after you have done editing. After all is done, you will have "hw.sh" in your home directory. Type "ls" (acting like dir in Windows) to see if it is there. Then type "sharpe hw.sh" to see the output. To redirect the output to a file "hw.out", type "sharpe hw.sh > hw.out". Then type ls again to see if hw.out is there. Type "cat hw.out" will allow you to see the content of hw.out.

If you are not familiar with UNIX commands, you can use the "man" command to understand how a UNIX command works. For example, "man vi" will tell you how to use the UNIX editor called "vi". Similarly "man ls" will tell how "ls" works.

If it is still too difficult to work in the UNIX environment, I suggest you transfer the PC version of sharpe into your home Windows PC. See the class homepage about how this can be done. Then follow the above instructions to create "hw.sh" and run "sharpe hw.sh > hw.out" except that you simply create your hw.sh using a PC editor and type in "sharpe hw/sh > hw.out" to run sharpe in a command window in the Windows environment.

>Another quick question is that, when I was doing this problem #3, I was assuming that all the paths are unidirectional. I just want to confirm this point with you.

In problem #3 part (a) for defining a reliability graph model, you need to specify whether an edge is uni-directional or bi-directional. In problem #3 part (c) for defining a fault tree model, there is no concept of unidirectional or bi-directional edges. Instead, you need to specify if any edge is repeated in your fault tree model.