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Unformatted text preview: our proof requires several similar subproofs, each containing a similar sequence of steps. To cut or copy a range of steps, you must first select the steps. Shift-clicking on a step will select the range of steps between the focus step and that step. You cannot select a range containing just one step, so shift-clicking on the focus step will do nothing. A grey will appear, showing which steps are selected. If the rectangle doesn’t contain the steps you want, click somewhere else in the proof and the rectangle will disappear. You can then try selecting the steps again. Note, however, that Fitch will not allow the selection rectangle to cut a subproof in half: you must either select steps entirely from within a subproof, or else select the subproof as a whole. When the rectangle contains exactly the steps you want, choose Cut or Copy from the Edit menu. Both of these commands place a copy of the steps on the clipboard; Cut also deletes the selected steps from the proof. Once a sequence of steps is on the clipboard, choosing Paste will insert the steps at the point of focus. If you are currently focused on an empty step, the pasted steps will replace the empty Using Fitch / 43 step. If you are currently focused on a step that is not empty, the pasted steps will be inserted after the focused step. If you want to paste steps into your proof immediately following a subproof, but not as part of the subproof, you will have to end the subproof before pasting. This will give you an empty step outside the subproof and Paste will replace this empty step with the steps on the clipboard. When you paste steps into a proof, Fitch will try to keep track of the appropriate supports for those steps. Sometimes, though, the supports for the pasted steps will no longer be “legal” in the new location, for example if you paste a step into the proof at a point earlier than one of its support steps. In such cases, Fitch will remove the illegal support from the step’s list of supports. Note that this method also gives you a handy way to delete a large number of steps. Rather than repeatedly choosing Delete Step from the Proof menu, simply select all of the steps you wish to delete, and choose Clear from the Edit menu. Simply hitting the Delete key will also delete the selected range of steps. 4.5 Printing proofs To print a proof, choose Print. . . from the File menu. When you do this, you will be given the standard print dialog box. Once you have chosen any printer options you want to use, click on the Print button in the dialog box. In the printed proof Fitch adds numbers to all of the steps and uses these numbers to indicate each step’s supports so that the printed proofs look like the proofs in the textbook. 4.6 Setting up exercises Fitch has two modes of operation, user mode and author mode. Students normally use the program in user mode, so exercise files are always opened in user mode. This mode allows you to construct proofs, but not to change the premises or go...
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This document was uploaded on 01/26/2014.

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