Tableaux using qtree

Here's a basic guide to formatting logical tableaux using Alexis Dimitriadis' qtree package.

First, you'll have to include the qtree package. Make sure qtree.sty is in your LaTeX path, and put the following command in your LaTeX document:

\usepackage{qtree}

Now you're ready to rock. The basic qtree container syntax for a node is this

\Tree
    [.{ }
    ]

Each node starts with "[." and ends with "]". The content of the node is contained within the braces "{ ... }". Hence, to start off your tree with an initial set of sentences, you do this:

\Tree
    [.{ sentence 1\\
        sentence 2\\
        sentence 3 }
    ]

Crucial to this is to use "\\" to indicate line breaks. This code gives you a tree with a single node. Not much to look at, but the magic is coming soon. To add new nodes under this one, you add additional node containers, where each node container is, as in the first case,

       [.{ new node }
       ]

Thus, to add a single node to your tree, you do this:

\Tree
    [.{ sentence 1\\
        sentence 2\\
        sentence 3 }
      [.{ first new node }
      ]
    ]

To add two nodes, you do this:

\Tree
    [.{ sentence 1\\
        sentence 2\\
        sentence 3 }
      [.{ first new node }
      ]
      [.{ second new node }
      ]
    ]

Once you've gotten this far, you know everything you need to make logical tableaux of any complexity. Extend the tree where you like by nesting new node containers in the appropriate locations. For instance, to add a single new node to the left node, do this:

\Tree
    [.{ sentence 1\\
        sentence 2\\
        sentence 3 }
      [.{ first new node }
        [.{ new subnode }
        ]
      ]
      [.{ second new node }
      ]
    ]

And, just for fun, we can add two new nodes to the right node:

\Tree
    [.{ sentence 1\\
        sentence 2\\
        sentence 3 }
      [.{ first new node }
        [.{ new subnode 1 }
        ]
      ]
      [.{ second new node }
        [.{ new subnode 2 }
        ]
        [.{ new subnode 3 }
        ]
      ]
    ]

Here's an example tableaux that was part of a problem set:


\Tree
    [.{
	$(E \to B)$\\
	$\checkmark (\lnot H \lor (P \land T))$\\
	$(T \to (E \lor M))$\\
	$\checkmark (( E \lor (H \land \lnot T)) \to \lnot P)$\\
	$\checkmark \lnot ((\lnot H \lor E) \to ( (E \land M) \to \lnot H))$
      }
      [.{
	  $\checkmark (\lnot H \lor E)$\\
          $\checkmark \lnot ((E \land M) \to \lnot H)$
	}
	[.{  
            $\checkmark (E \land M)$\\
	    $\checkmark \lnot \lnot H$
	  }
	  [.$H$ 
	    [.{
		$E$\\
		$M$
	      }
	      [.{$\lnot H$}
		[.$\otimes$ ]
	      ]
	      [.$E$
		[.{$\lnot H$}
		  [.$\otimes$ ]
		]
		[.{$\checkmark (P \land T)$}
		  [.{
		      $P$\\
		      $T$
		    }
		    [.{$\checkmark \lnot (E \lor (H \land \lnot T))$}
		      [.{
			  $\lnot E$\\
			  $\lnot (H \land \lnot T)$
		      }
			[.$\otimes$ ]
		      ]
		    ]
		    [.{$\lnot P$}
		      [.$\otimes$ ]
		    ]
		  ]
		]
	      ]
	    ]
	  ]
	]
      ]
    ]

There's only one more thing to remember. For some reason, pdflatex does not like to play with qtree. I've needed to use latex, then dvips and then convert the resulting postscript file into pdf.

Ang Tong
October 5, 2005