Fri, Feb 15, 2008 - Page 21 News List

And along come two at once... 起而行不如坐著等

Pakistan men read newspapers at a bus stop a day after President Pervez Musharraf declared a state of emergency, in Islamabad, Nov. 4, 2007.
二OO七年十一月四日,巴基斯坦幾名男子在總統穆沙拉夫宣布全國進入警戒狀況的隔天,在伊斯蘭馬巴德的一處公車站看報紙。照片:法新社

PHOTO AFP

People frustrated by the delayed arrival of a bus should take the lazy option and wait for it to show up rather than walk to their destination, mathematicians say.

Number crunchers from Harvard University and the California Institute of Technology (Caltech) drew up a formula to calculate whether waiting or walking was the best option for those facing a sporadic bus service.

Their equation has these variables : n, for the number of bus stops spaced along the bus route; d, for the distance along the bus route; Vw, being the bus speed; Vb, the walking speed; and p(t), being the probability in time that a bus will show up.

Their verdict: stick around and wait for the bus at the first stop. If you set off walking, there is a comparatively greater risk that the bus will zoom past before you reach the next stop on the route.

"The answer is intuitive: the optimal strategy is the laziest," the mathematicians say.

Walking becomes the smarter option, though, if the distance to be traveled is less than 1km and there is at least an hour between buses, the investigators told the British weekly New Scientist.

The paper, by Justin Chen, Scott Kominers and Robert Sinnott, appears online in the open-access library of New York's Cornell University. (AFP)

數學家建議,那些等拖班公車等得不耐煩的民眾還是放鬆心情等公車來比較好,不要自己走到目的地。

來自哈佛大學和加州理工學院的數學家們制定了一個公式,計算等待或走路何者才是面對姍姍來遲的公車的最佳選擇。

這項公式包含以下的變數:n表示公車路線中的站牌數量;d表示公車路程總長;Vw表示公車行駛速度;Vb表示步行速度;p(t)公車及時出現的機率。

他們的結論是:待在原地等公車來。假如你開步往前走,公車在你抵達下一個站牌前,從你身邊呼嘯而過的風險就相對較大。

數學家說:「相信你的直覺:懶為上策。」

然而,研究者對英國週刊《新科學家》表示,若目的地距離在一公里以內,且公車在一小時內不會來,步行則是較聰明的選擇。

這份由賈斯丁.陳、史考特.寇明納和羅柏.席諾特發表的論文收錄於紐約康乃爾大學的線上圖書館,供大眾公開查閱。

(法新社/翻譯:袁星塵)

OUT LOUD 對話練習

Adam: Man! We've been waiting for this bus forever! Maybe we should just walk.

Kelly: No, if we start walking the bus is sure to come along as soon as we're five minutes down the road. And it'll probably drive through a big puddle and soak us.

Adam: Yeah. Murphy's Law and all that.

Kelly: You could start walking though, just to test it. I'll wait here.

Adam: No, it's all right. I'll wait with you.

亞當:喂!我們已經等這號公車等了八百年了!也許我們該用走的。

凱莉:不,如果我們現在開始走,公車一定會在五分鐘內來的,而且它說不定還會開過一個大水坑把我們濺濕。

亞當:是啊,莫非定律以及諸如此類的嘛。

凱莉:不然你開始走,我在這裡等,我們來測試看看好了。

亞當:不用了啦,我跟妳一起等。

Murphy's Law 莫非定律

Murphy's Law refers to the idea that if anything can go wrong, it will, with the worst possible result or timing.

「Murphy's?Law」指的是會出錯的事,就一定會出錯,而且還是以最糟的可能結果或時機出錯。


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