Here are some conventions:

In Carnap, you indicate that a line is a premise by writing :PR to the right of the premise. Carnap will render the proof nicely, off to the right. For instance, it will draw a line under the last premise.

You have to write the steps leading to the conclusion underneath. Each line will have a sentence in it$,$ and a justification separated by a colon : to the right. For instance, to justify line $2$ by $$E from line $1$ you'd enter :&E $1$ next to the sentence A being justified. $($Note: there must be no space between : and &E$.)$ A line will get a $+$ next to it once you have entered a correct justification. If the justification is incorrect, you'll get a $?$ or a $.$ Carnap will try to tell you what's wrong: hover the cursor over the $?$ or $$ to see a hint.

Remember to separate the two subproofs by $--.$ This line should not be indented. The video lecture will show exactly how do deal with this symbol.

When you work for a score, However, Carnap will not save work on this page, and it won't show which problems you already have submitted correctly! So you should keep track of which problems are done, and copy any work you want to save and paste it into a text document for later use or reference. You can also print the problem page with completed problems, or take screenshots.

To enter logical symbols on the keyboard, use:

not $-,$ ~and $/\backslash ,$ &or $\backslash /$if then $->,>$if and only if contradiction $!?,\_|\_$

Give a formal proof of the following argument.