Exercise 1.6
The text labels each proposition in the argument with a numeral. When the page appears the argument with its numbering is shown on the left and on the right is a white field bordered in black. The diagram is drawn on this field.
The circles are stacked across the top of the work
field. They are positioned by dragging and dropping. For programming purposes, only certain
positions may contain a circle. LogicCoach
will move a circle that is dropped to the next position. It may take some practice before you able to
place a circle exactly where you want it.
To facilitate finding the spot, draw the target grid. The center 
of the drag icon goes on the center of the
target.
Joint premises (and joint conclusions) must be on the same horizontal line of the diagram. To facilitate this placement, if a circle is dropped on another, it is placed in the next open position on the same line.
Above the field, at its left corner, are three boxes.
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Enables program to... |
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Drag |
drag and drop number circles |
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Draw |
draw connections among the propositions |
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Erase |
erase drawn connections |
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The active function is shown in green. Clicking on Draw or Erase displays an additional three boxes that show which drawing the program will make or break. They too are selected among by clicking. Again, the selection is shown in green.
To connect or draw, click on the two circles which are to be connected. When you click on the first, it will turn green. (To cancel this selection, click on the same circle again.)
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Label |
Connects or Draws... |
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↓ |
a black inference arrow from the circle on top to the circle on the bottom. The one on top is selected as premise and the one on the bottom as conclusion. If the connected circles are repositioned, the circle now on top becomes the premise. |
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∩ |
a blue bar across the top of the two circles indicating that they are joint conclusions. The numbers in the circles are also changed to blue. Either may be clicked on as the destination for an inference arrow but it will be drawn to the second one on the right. Note: If there are to be three or more joint conclusions, each new one in turn must be connected to one of the others already jointly connected. |
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∪ |
a red bar across the bottom of the two circles indicating that they are joint premises. The numbers in the circles are also changed to red. Either may be clicked on as the origin for an inference arrow but it will be drawn from the second one on the right. Note: If there are to be three or more joint premises, each new one in turn must be connected to one of the others already jointly connected. |
To break or erase a connection, click on the premise of the inference or either of the joint premises or conclusions.
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Label |
Breaks or Erases ... |
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↓ |
all inference arrows leading from the clicked on circle. |
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∪ |
the clicked on conclusion from its connection to the others with which it is a joint conclusion. If there is only one other, then the blue bar disappears. If there are two or more remaining joint conclusions, the others remain connected. |
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∩ |
the clicked on premise from its connection to the others with which it is a joint premise. If there is only one other, then the red bar disappears. If there are two or more remaining joint premises, the others remain connected. |