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Unformatted text preview: als of the proof, which
of course is not permitted in solving the exercises. (The Grade
Grinder always checks to make sure that no changes have been
made to the premises or goals of a proof.)
Author mode is used for creating new exercises, and so new 44 / LPL Software Manual ﬁles are always opened in author mode. This mode allows you to
enter premises into the proof, add goals to the proof, and specify
any constraints that apply to the goals.
You can tell which mode you are in by looking at Author
Mode on the Edit menu. If there is a check in front of Author
Mode, Fitch is in author mode; otherwise, it is in user mode.
Choosing Author Mode will toggle between these two modes.
The current mode is saved with the ﬁle, so if you create a
new problem, you should turn oﬀ author mode before saving it.
Alternatively, you can use Save As Problem. . . from the File
menu. This command is available only in Author Mode, and will
save only the premises and goals in the new ﬁle. The created ﬁle
is saved in user mode. 4.6.1 Adding and deleting premises To add a premise, you must be in Author Mode. Choose Add
Premise from the Proof menu. If you are currently focused on
a premise step, the new premise will appear immediately after the
focused step. If you are focused on a step in the body of the proof,
the new premise will appear at the end of the list of premises.
To delete a premise, focus on its step and choose Delete Step
from the Proof menu. 4.6.2 Adding and deleting goals To add a goal to a problem, choose New Goal from the Goal
menu and enter the goal sentence you want. As noted above, this
can only be done in Author Mode. To delete a goal from a problem,
click on the goal in the goal strip and choose Delete Goal from
the Goal menu.
You can check use the Check Goal Forms from the Goal
menu to check that the goal formulas are well formed. Goals that
are not well formed will be marked with a star.
If you want to modify the constraints on a goal, choose Edit
Goal Constraints from the Goal menu. When you initially add
a goal, Fitch assumes that you want the goal to be proven using
just the introduction and elimination rules of F . If you want to
allow the use of the Con procedures, or if you want to disallow the
use of any standard rules, you will have to modify the constraints Using Fitch / 45 Figure 4.3: Fitch Preferences Dialog
associated with the goal. Constraints are associated with individual goals, so a problem can have diﬀerent constraints for diﬀerent
goals. 4.6.3 Saving new problems To save a newly created ﬁle as an exercise to be solved, choose
Save As Problem. . . from the File menu. This saves the ﬁle,
but also turns on User Mode in the ﬁle, so that users will not
accidentally change the premises or goals of the exercise. 4.7 Preferences Some aspects of the behavior of Fitch can be controlled using the
preferences dialog. This can be accessed by choosing the Preferences... command from the application menu (Edit Menu on
Windows). The preferences dialog is shown in ﬁgure 4.3.
The preferences allow you to control the style of text for sen...
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This document was uploaded on 01/26/2014.
- Winter '14