EL DRENAJE ACIDO DE MINA

Economists consider auctions as one of oldest surviving classes of economic institutions [4]. One of the earliest reports of an auction was from interpreting the biblical account of the sale of Joseph (the great son of Abraham) into slavery as being an auction sale [5]. Another report was by the Greek historian Herodotus, who described the sale of women to be wives in Babylonia around the fifth century B.C. [6-7] these auctions use to begin with the woman the auctioneer considered the most beautiful and progressed to the least. In fact, at that time, it was considered illegal to allow a daughter to be sold outside of the auction method. During the closing years of the Roman Empire; the auction of plundered booty was common, following military victory, Roman soldiers would often drive a spear into the ground around which the spoils of war were left, to be auctioned off. Later slaves, often captured as the "spoils of war", were auctioned in the forum under the sign of the spear, with the proceeds of sale going towards the war effort [6]. Moreover, the personal belongings of deceased Buddhist monks were sold at auction as early as the seventh century A.D. in China. In some parts of England during the seventeenth and eighteenth centuries auction by candle was used for the sale of goods and leaseholds. This auction began by lighting a candle after which bids were offered in ascending order until the candle spluttered out. The high bid at the time the candle extinguished itself won the auction [8]. During the end of the 18th century, French started auctioning art, soon after the French Revolution, daily in taverns (which was used to be considered as a place of business and social activities) and coffeehouses, during these auctions, catalogues used to be printed to show available items. Which lead us to mention the oldest auction house in the world, known as “Stockholm Auction House”, it was established in Sweden in 1674 *9-10].

As impressive as the historical facts of auctions is the remarkable range of situations in which they are currently used in our day-to-day life. There are auctions for livestock, auctions for rare and unusual items like diamonds, work of arts and other collectibles. Reports from recent researches can be seen in the United States in the 1980’s, where every week, the U.S. treasury sells billions of dollars of bills and notes using a sealed-bid auction. The Department of the Interior sells mineral rights on federally-owned properties at auction. Furthermore, many examples can be seen throughout the public and private sectors, purchasing agents solicit delivery-price offers of products ranging from office supplies to specialized mining equipment; sellers auction antiques and artwork, flowers and livestock, publishing rights and timber rights, stamps and wine and many other market transactions [4]. From the academic point of view, [11-12] can be considered as one of the influential contributions of auction theory; it was followed by a large amount of literature, which examined the behaviour of competitive bidders in auctions. [13-15] define an auction to be a market institution with an explicit set of rules determining resource allocation and prices on the basis of bids from the market participants. Consequently, the auctioned good is to be sold with a price resulted from direct competition of the potential buyers, who know exactly their individual willingness to pay better than the seller. Finally, the development of the internet, however, has led to a significant increase in the use of auctions as sellers can seek for bids via the internet (such as the bidding system in eBay [16-17]) from a wide range of buyers in a much wider range of commodities than was previously practical [6].

It is important to mention that for several reason this work is restricted to the discussion of a single object auctions. On one hand, in order to analyze such auctions, it might get rather difficult if multiple objects are to be allocated. On the other hand, the results derived for single unit auctions definitely give a good understanding over the effects auction rules and behavioural assumptions have on the bidding behaviour.

Generally speaking, there are four standard auctions that are discussed in the literature [2-5]. These standards are; the ascending-bid auction (known as the English auction), the descending-bid auction (known as the Dutch auction), first-price auction and the second-price auction (known as Vickery auctions). All of these auctions apart from Vickery auction are used in business transactions, while Vickery auctions is rarely used but it has some theoretically appealing properties. These mechanisms assigns the highest bidder to be a winner, however, they can be classified basically by two main factors. Firstly the

bidders can submit open or sealed bids; secondly the price may be determined by the highest or the second highest bid.

The ascending-bid auction is the most common auction form. In this type of auctions, the price is successively raised until only one bidder remains. This can be done either by the auctioneer, announcing prices, or by the bidders calling for higher bids themselves. Thus, the remaining bidder receives the object paying only the second highest bid. A very important feature of this auction is that each bidder knows the current highest bid at any point in time.

The descending-bid auction is the converse of the ascending-bid auction. The seller begins by announcing a price that exceeds the willingness to pay of every bidder (i.e. a very high price). Then he lowers the price until one bidder accepts the actual offer. This bidder pays the price at which he claimed the object.

In the first-price sealed-bid auction bidders submit sealed bids and the highest bidder gets the object for the price he bid. In the second-price sealed-bid auction, however, the highest bidder is awarded the item and pays the second highest bid.