A circus has seven fenced enclosures, numbered 1 through 7, for two animals: a lion and a tiger. Each enclosure is connected to adjacent enclosures by interior gates. There are exactly eight such gates, each connecting one enclosure to exactly one other enclosure: enclosure 1 is connected to enclosures 2, 3 and 4; enclosure 3 to enclosures 1, 2, 4, and 5; and enclosure 5 to enclosures 3, 6, and 7. These gates provide the only connections between enclosures. Occasionally a trainer moves the animals. Taking either animals from one enclosure to an adjacent enclosure through a gate is called a "transfer."
The following conditions are strictly observed:
The two animals cannot be together in any enclosure or gate.
Transfers cannot occur simultaneously In moving either one animal or both to a specified enclosure or enclosures, the minimum number of trans- fers needed to achieve the specified result are used.
Five participants at an international conference are planning to take a car trip together. Two persons? the driver and one passenger? will sit in the front seat of the car, and three persons will sit in the back seat. The names of the five participants and all of the languages that each of them speaks are as follows:
Mohsen: Farsi and Hebrew
Orlando: Italian and Russian
Shelly: Hebrew and Russian
Theo: German and Italian
Ursula: Farsi, German, and Hebrew
The participants must be seated in the car according to the following restrictions:
The driver must be Orlando or else Shelly.
Two persons can be seated side by side only if at least one of the languages they speak is the same.
The organizers of a music festival are scheduling exactly six master classes, one class per day for six consecutive days. Three of the classes will be given by violinists and three by pianists. The only musicians who can teach the classes are the violinists F, G, H, and J, and the pianists R, S, T, W, and Z. The festival's organizers must observe the following constraints:
No musician will teach more than one class.
F will not teach unless the first three classes are taught by violinists.
If J teaches a class, it will be the sixth.
R will teach only if T teaches the first class.
No pianist will teach on a day that immediately precedes or immediately follows a day on which W teaches.