Inventory models assign an important role to market-makers who offer the opportunity to trade at all times and therefore act as immediacy providers. The initial modelling approach (Garman, 1976) to the market-makers’ control problem assumes that their objective is to avoid bankruptcy (the ‘ruin problem’), which could be caused by the uncertainty induced by the arrival of non-synchronous buy and sell orders. As O’Hara (1995) suggests, this approach is not realistic since it assumes that a dealer quotes his prices only at the beginning of the trading game, so his inventory plays no role in the decision.

The next two articles are dedicated to models that focus on the adverse selection component of the bid–ask spread. It will also discuss inventory and fixed costs. The model presented in this chapter draws on the work of Kyle (1985), who posits a group of risk-neutral market-makers facing insiders and liquidity traders. In fact, Kyle models the strategic interaction between an insider who chooses to trade in order to maximize his profits and a group of market-makers who take the insider’s strategy into account in updating their beliefs on the future value of the asset and setting the equilibrium price. In this way, Kyle shows how information is incorporated into prices and how the latter reflect both the trading protocol where market-makers set prices and the strategic behaviour of the informed trader.

The United States patent database is huge and complicated, and it would be foolhardy for novice inventors to believe that they could do thorough enough searches to base utility patent applications on them. But, with a little bit of instruction in how to get around on the USPTO website, anyone can do a pretty good preliminary search. What we mean by a preliminary search is this: if you go into the USPTO database and, with a limited amount of searching, you find your invention idea staring back at you; it is time to reassess your idea. Is the prior art (patent) that you just found your exact idea? If it is not, is your idea an improvement over that product? If you believe it to be your exact idea, it is probably best to set it aside and move on to your next idea before you spend any more time or any money on it. But, if you think your idea is significantly different or better, print that patent and take it to a patent agent or attorney for a legal opinion.

If you find a patent that appears to be your exact idea, be sure to read the claims section carefully to make sure that it truly is identical before you abandon your dream. Sometimes two products can be made for the exact same purpose and they can look very similar or even identical in patent drawings and still be very different in the embodiments of how they are actually made.

Or, they will be your competition if you plan to build a business around your invention. Either way, it will be to your advantage to know as much as you can about these companies that manufacture products similar to your invention. If your invention is something that is not specifically a retail item, such as a medical invention that would be sold through specialty outlets, you will need to track down those specific outlets and catalogs (perhaps with the help of a medical professional) in order to search in that area. However, if you have developed such an invention, chances are excellent that you are already familiar with those specialized outlets.

If your invention is in a field that is a specialized area in which the products are not found in the usual retail outlets, you may need assistance from professionals in that industry during your research or development phase. Be sure to have each person who assists you to sign a non-disclosure document for your files.

Small Business Development Centers can also provide information and guidance on how to apply for and obtain Small Business Administration loans through your local bank or credit union.

Individuals often make and sell products on the Internet that are offered nowhere else. If you neglect to do a good Internet search, you will miss this prior art. What is prior art?

If an active patent covers a product, you cannot legally make and sell it.

If that patent has expired, that product is said to be in the public domain and is now available to anyone to make and sell.

A product that has never been patented but has been offered for sale to the public is also said to be in the public domain and can never be patented.

All of the above examples are prior art; products that have already been presented to the public and cannot now be patent protected. One of the first things the examiners at the patent office will do when they begin with your application is to initiate a thorough search for prior art. If you failed to find these products but they were found in subsequent searches related to your patenting efforts, your patent would be rejected and you would have spent your money and your time in vain. It pays to be meticulous in your Internet  searching.