Only the Sultan knows what things are "jewels." Everything else is sand in the desert. The Jewel Thief devises sieves to sift jewels from sand.
EQUIPMENT
- Blank paper
- Blue and yellow highlighters/markers
- Blue Post-it Notes ("jewels")
- Yellow Post-it Notes ("sand")
- Pencils
Note: the blue and yellow colors above are merely for easy visual recognition - any two distinct and contrasting elements in color/texture/pattern may be used.
SETUP
Create a playing board on a sheet of paper by "crosshatching" the top half with a blue highlighter (to suggest wire mesh) and label it "SIEVE". Use the yellow highlighter to "dot" the bottom half of the board (to suggest a sandy surface) and label it "DESERT". Leave a blank area or use another sheet and label it "CAMPSITE."
GAMEPLAY
One player is the "Sultan". The other player is the "Jewel Thief."
"Jewel Rules" and "Sieve Rules" are descriptions for any set of objects, concrete or abstract.
Some examples might be "movie stars," "numbers divisible by seven," "colors," "things that float," "round objects," "words containing double letters," "shapes that can be drawn without lifting the pencil from the paper," "government agencies."
The Sultan thinks of a "Jewel Rule", recording it on a slip of paper and concealing it from the Jewel Thief. Anything fitting the description of this rule is a jewel. Everything else is sand.
On a blue Post-it, the Sultan writes an example of a jewel (ie, something identified by the Jewel Rule). On a yellow Post-it, he writes an example of sand (ie, something that does NOT fit the Jewel Rule). Then he places both in the DESERT. For example, if the Jewel Rule were "words with double letters", an example of a jewel might be "glass" and an example of sand might be "window."
The jewel thief, considering the jewels and sand revealed by the Sultan, guesses a "Sieve Rule" and records it in the CAMPSITE. The Sieve Rule should be capable of sifting all currently revealed jewels from sand revealed so far.
The jewel thief moves any jewels (i.e., blue Post-Its) to the SIEVE, and any sand (i.e., yellow Post-Its) to the DESERT to demonstrate that his Sieve Rule properly sifts all the revealed jewels from the revealed sand so far.
If the Sieve Rule does not match the Jewel Rule, the Sultan must prove it. He does so by revealing, if possible, another jewel that slips through the SIEVE into the DESERT.
He must also, if possible, reveal another sand object that is erroneously caught by the current SIEVE. In other words, the Sultan will place both a new blue Post-it on the yellow desert area, and a new yellow Post-it on the blue sieve area -- when possible.
Three different conditions may arise:
- It may happen that the Sieve Rule is a subset of the Jewel Rule. In this case, the SIEVE "catches" no sand, only jewels. However, since it is only a subset of the Jewel Rule, it allows some jewels to slip through erroneously into the DESERT. Thus, the Sultan can identify a new jewel in the DESERT that the current SIEVE does not catch, but there will be no sand in the SIEVE for the Sultan to identify.
- On the other hand, the sieve rule may be a superset of the jewel rule. In this case, the SIEVE catches all jewels, allowing none to slip through into the DESERT. However, as a superset, it erroneously catches some stray sand along with the jewels. Thus, the Sultan can identify a new sand object in the current SIEVE, but there are no jewels in the DESERT for the Sultan to identify.
- In the typical case, however, the SIEVE is a normal "intersection", where the SIEVE erroneously allows some jewels to slip through and mistakenly catches some sand. Thus, it will be possible for the Sultan to reveal both a sand object caught by the SIEVE, and a jewel that slips through into the DESERT.
If the new Sieve Rule is still not correct, the Sultan proves it by using the same process of revealing new objects outlined above.
When the sieve rule is finally correct (or, in what amounts to the same thing, the Sultan cannot think of objects to disprove the sieve rule, even though the sieve rule may be worded differently from the jewel rule), the Sultan gets five points for each jewel object revealed plus one point for each sand object revealed.
The other player becomes the new Sultan to complete the round. The player with the most points after a predetermined number of rounds wins the game.
Note: The game, as is, relies on both players' interest in the deduction process to encourage the Sultan not to choose an "impossible-to-guess" Jewel Rule. A box of pre-selected Jewel Rules to choose from in any kind of marketed production of the game could ensure this condition.
