We shall number the cards 1, 2, 3 and 4, 1 being the topmost card, 4 being the card on the bottom.
I put to you the following proposition:
If a card has a circle in it's left half, then it also has a circle in it's right half.
Now:
1) What's the least number of cards that must be completely uncovered to see that the proposition is true.
2) Which cards are these?
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