Nrthugu

I have to edit a LaTeX template for an assignment, which involves solving multiple choice questions. The code for one of these questions is as follows :

begin{list}{$square$}{}

setlengthitemsep{-1.5em}

item The current observation $x_t$ is conditionally independent of all 

 other observations given the current state $y_t$\

item The current observation $x_t$ is conditionally independent of all 

other states given the current state $y_t$\

item The current state $y_t$ is conditionally independent of all states given the previous state $y_{t-1}$\

item The current observation $x_t$ is conditionally independent of $x_{t-2}$ given the previous observation $x_{t-1}$.\

item None of the above

end{list}

The problem with this is that I don't know how to mark my answers (only two of these choices are right, and should be marked with a black square). I've tried to remove the {$square$} from the first line, and add $square$ next to each item, with $blacksquare$ next to the options I want marked.

begin{list}{}

setlengthitemsep{-1.5em}

item $square$ The current observation $x_t$ is conditionally independent 

 of all other observations given the current state $y_t$\

item $square$ The current observation $x_t$ is conditionally independent 

 of all other states given the current state $y_t$\

item $square$ The current state $y_t$ is conditionally independent of all 

 states given the previous state $y_{t-1}$\

item $square$ The current observation $x_t$ is conditionally independent 

 of $x_{t-2}$ given the previous observation $x_{t-1}$.\

item $square$ None of the above

end{list}

And that worked for the previous question. But with this one, when I do it and compile, this happens.

It's that pesky !-1.5em. And I don't know how to get rid of it. I tried removing the setlengthitemsep{-1.5em} but that results in the spacing between items increasing to whatever the default value was and the contents of this page spill over onto the next one, which is unacceptable to the autograder. What do I do? It's incredibly annoying.

This is the error I get at the setlengthitemsep{-1.5em} line. (I've tried putting the itemsep in curly brackets too, as an answer said, to no avail.)

The list environment takes two arguments and in your second example you are only feeding it one. It therefore uses the next token, which is setlength, as its second argument. Using begin{list}{}{} instead of begin{list}{} therefore removes the error.

As for the problem you were originally trying to solve: the item macro has an optional argument which you can use to specify its label. The following should thus do what you want.

documentclass{article}



usepackage{amssymb} %% <- for square and blacksquare



begin{document}



begin{list}{$square$}{}

setlengthitemsep{-.4em}

item The current observation $x_t$ is conditionally independent of all 

 other observations given the current state $y_t$

item[$blacksquare$] The current observation $x_t$ is conditionally independent of all 

other states given the current state $y_t$

item[$blacksquare$] The current state $y_t$ is conditionally independent of all states given the previous state $y_{t-1}$

item The current observation $x_t$ is conditionally independent of $x_{t-2}$ given the previous observation $x_{t-1}$.

item None of the above

end{list}



end{document}

You could save yourself some typing by e.g. defining

newcommand*correctitem{item[$blacksquare$]}

and using that instead of typing it out every time.

Incidentally, the contents of the second argument of list is executed right before the start of the actual list.
It would be more appropriate to put setlengthitemsep{-.4em} inside this argument, like this:

begin{list}{$square$}{setlengthitemsep{-.4em}}

For itemsep it makes little difference, but if you want to set e.g. topsep, doing this inside the environment is actually too late.

Instead of going crazy setting the itemsep you could use enumitem package with nosep option.

documentclass{article}

usepackage{amssymb} 

usepackage{enumitem}

renewcommand{labelitemi}{$square$}

begin{document}

begin{itemize}[nosep]

item The current observation $x_t$ is conditionally independent of all 

 other observations given the current state $y_t$

item[$blacksquare$] The current observation $x_t$ is conditionally independent of all 

other states given the current state $y_t$

item[$blacksquare$] The current state $y_t$ is conditionally independent of all states given the previous state $y_{t-1}$

item The current observation $x_t$ is conditionally independent of $x_{t-2}$ given the previous observation $x_{t-1}$.

item None of the above

end{itemize}

end{document}