Myujth

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 :

beginlist$square$
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
endlist

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.

beginlist
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
endlist

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 beginlist instead of beginlist 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.

documentclassarticle

usepackageamssymb %% <- for square and blacksquare

begindocument

beginlist$square$
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
endlist

enddocument

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

newcommand*correctitemitem[$blacksquare$]

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:

beginlist$square$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.

documentclassarticle
usepackageamssymb 
usepackageenumitem
renewcommandlabelitemi$square$
begindocument
beginitemize[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
enditemize
enddocument