Supply Chain and Operations Management Glossary (G)
Gambler’s Ruin: A characterization of the fact that even if the odds are in our favor, we may still go broke when facing a bigger competitor in a situation where chance plays a role. Specifically, if at each encounter, we either win a dollar from our competitor with probability p or lose a dollar with probability q = 1-p. Then, our starting wealth is $w and our competitor’s wealth is $u and the probability that our competitor will go broke before we go broke, is: [1-(q/p)w]/[1-(q/p)w+u]. Verify that even if p > 0.5, if u is large relative to w, the probability is low that our competitor will go broke first. In the special case when p = 0.5, the probability that our competitor goes broke first simplifies to w/(w+u). See also Lanchester equations. GATT (General Agreement on Trade and Tariffs)
GHz (Giga Hertz): Billion cycles per second.
GIS (Geographical Information System): A system based around an accurate, detailed database of all
streets, highways, addresses, and other physical features in a region, usually complemented with a
graphical display capability. Also see TIGER. GL (General Ledger): An aggregate summary of account balances of the firm (e.g., it contains summaries of AR, AP, Payroll, etc.).
GPS (Global Positioning System): A system for accurate determination of a vehicle’s position, based on accurately measuring the distance to four or more satellites. The satellites transmit precisely synchronized signals based on a very accurate clock in each satellite. The receiver estimates distance from each satellite and, thus, its location by observing the phase differences of the signals from the satellites.
Gray market: The reselling of a product in a “market” other than which it was bought and in which the manufacturer intended. For example, some software vendors have charged less for a product in the U.S. market than in the European market. Thus, some arbitragers have been tempted to buy the product in the U.S. and resell it in Europe, thus possibly reducing the profits of the manufacturer. See revenue management.
Great Circle Distance: Shortest distance between two points over the surface of the earth. If LATi is the latitude of point i in radians, and LONGi is the longitude of point i in radians, then the great circle distance in miles between cities i and j is 3959*acos(sin(LATi)*sin(LATj)+cos(LATi)*cos(LATj)*cos(ABS(LONGi-LONGj))). Note that 3959 is the approximate radius of the earth in miles. Degrees can be converted to radians by multiplying by 3.1415926/180. ACOS is the arc cosine.
Group technology: A methodology, largely of European origin, for classifying parts to be manufactured into classes or groups, so that parts that are close together in the classification tend to be
manufacturable by the same methods.
GTIN (Global trade item number): A code, similar to UPC, for identifying products or SKU’s.
Hazmat: hazardous material. Examples include flammable, explosive, poisonous, radioactive, and corrosive materials. In the U.S., the Office of Hazardous Materials Operations in the DOT enforces regulations regarding the transportation of hazmat.