梦幻级的玩具，唯一的问题是……要200,000,000＄(including two air vehicles, the control station, payload, ground equipment, training, and logistics package)
看来除了军方以外()，能玩儿得起的人不多。就算是军方都嫌有点儿贵了，一辆Hammer卖给US Army的批发价才10万＄。

http://www.schiebel.net/ 

Technische Daten CAMCOPTER® S-100 VTOL UAV
Rumpflänge: 3,091m
Rumpfbreite: 0,51m
Landekufenbreite: 1,238m
Höhe über alles: 1,042m
Hauptrotor-Durchmesser: 3,400m
Leermasse: 97kg
max. Abflugmasse: 200kg
max. Nutzlast: 50kg
Antrieb: 55PS (40kW) Flugzeugmotor in Wankel-Technik
Geschwindigkeit bei geringstem Benzinverbrauch: 55kt / 100km/h
Maximalgeschwindigkeit: 120kt / 220 km/h
max. Flughöhe: 18.000ft MSL / 5.487m
Treibstoffkapazität: 58 Liter
max. Einsatzdauer: bis zu 6 Stunden mit 25kg Nutzlast
typischer Einsatzradius: bis zu 180 km je nach Größe der Bodenantennen der Datenlinks
Navigation: Redundantes INS und GPS
Autonomie: Vollautomatischer Start, Wegpunktnavigation und Landung
Datenlink: zwei simultane, volldigitale Links mit bis zu 180km Reichweite

摘自海军陆战队的野外生存指南之刀具选择篇。

 

这里没有什么隐喻，完全是出于实用的考虑。

 

郑重声明：此玛丽莲非彼玛丽莲

这里说的是Marilyn vos Savant (born August 11, 1946)，一个专栏作家，因为Andrew Wiles在证明费马定理Fermat's last theorem过程中使用了非欧几里德几何方法而拒绝相信他的证明（当然还有其他一些更显著特征，比如小时候的IQ有228，据说到2003年为止都是the world's highest）。跟那个更著名的Marilyn Monroe (June 1, 1926 – August 5, 1962) 应该没什么关系。

 

OK，那么这个玛丽莲有什么问题要我们来操心呢？

The problem

Here is a famous statement of the problem, from a letter from Craig F. Whitaker to Marilyn vos Savant's column in Parade Magazine in 1990 (as quoted by Bohl, Liberatore, and Nydick):

Suppose you're on a game show, and you're given the choice of three doors: Behind one door is a car; behind the others, goats. You pick a door, say No. 1, and the host, who knows what's behind the doors, opens another door, say No. 3, which has a goat. He then says to you, "Do you want to pick door No. 2?" Is it to your advantage to switch your choice?

Figure1. In search of a new car, the player picks door 3. The game host then opens door 1 to reveal a goat and offers to let the player pick door 2 instead of door 3.

 

看得云里雾里？No Problem！这儿有更explicit的表述：

An unambiguous statement of the problem, with explicit constraints on the host as described by Mueser and Granberg:

• The player picks one of three doors. The contents are not revealed.
• The game host knows what is behind every door.
• The game host must open one of the remaining doors and must make the offer to switch.
• The game host will always pick a goat.
  • If the player picks a goat, the game host picks the other goat.
  • If the player picks the car, the game host randomly picks either of the two goats.
• The player is asked whether to stay with their first choice, or switch to the one remaining door.

Do the player's odds increase by switching?