UML use case diagram - System of goods selling via catalogues

"A catalog merchant (catalogue merchant in British and Canadian English) is a form of retailing. The typical merchant sells a wide variety of household and personal products, with many emphasizing jewelry. Unlike a self-serve retail store, most of the items are not displayed; customers select the products from printed catalogs in the store and fill out an order form. The order is brought to the sales counter, where a clerk retrieves the items from the warehouse area to a payment and checkout station. ...
The catalog merchant has generally lower prices than other retailers and lower overhead expenses due to the smaller size of store and lack of large showroom space.
There are a few key benefits to this approach. By operating as an in-store catalog sales center, it could be exempt from the "Resale price maintenance" policy of the manufacturers, which can force conventional retailers to charge a minimum sales price to prevent price-cutting competition; it also reduces the risk of merchandise theft, known in the industry as shrinkage.
From the consumer's point of view, there are potential advantages and disadvantages. The catalog showroom approach allows customers to shop without having to carry their purchases throughout the store as they shop. Possible downsides include that customers may be required to give their contact information when an order is placed, take the time to fill out order forms, and wait a period of time for their order to be available for purchase. This wait may be days long, one of the chief vulnerabilities of the catalog showroom approach." [Catalog merchant. Wikipedia]
The UML use case diagram example "System of goods selling via catalogues" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Rapid UML solution from the Software Development area of ConceptDraw Solution Park.

"Algorithmic trading, also called automated trading, black-box trading, or algo trading, is the use of electronic platforms for entering trading orders with an algorithm which executes pre-programmed trading instructions whose variables may include timing, price, or quantity of the order, or in many cases initiating the order by a "robot", without human intervention. Algorithmic trading is widely used by investment banks, pension funds, mutual funds, and other buy-side (investor-driven) institutional traders, to divide large trades into several smaller trades to manage market impact and risk. Sell side traders, such as market makers and some hedge funds, provide liquidity to the market, generating and executing orders automatically.
A special class of algorithmic trading is "high-frequency trading" (HFT), which is often most profitable during periods of high market volatility. During the past years, companies such as Algorates have employed HFT strategies, recording high profits even during periods in which the markets have seen steep declines." [Algorithmic trading. Wikipedia]
The UML use case diagram example "Trading system usage scenarios" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Rapid UML solution from the Software Development area of ConceptDraw Solution Park.

"An issue tracking system (also ITS, trouble ticket system, support ticket, request management or incident ticket system) is a computer software package that manages and maintains lists of issues, as needed by an organization. Issue tracking systems are commonly used in an organization's customer support call center to create, update, and resolve reported customer issues, or even issues reported by that organization's other employees. An issue tracking system often also contains a knowledge base containing information on each customer, resolutions to common problems, and other such data. An issue tracking system is similar to a "bugtracker", and often, a software company will sell both, and some bugtrackers are capable of being used as an issue tracking system, and vice versa. Consistent use of an issue or bug tracking system is considered one of the "hallmarks of a good software team".
A ticket element, within an issue tracking system, is a running report on a particular problem, its status, and other relevant data. They are commonly created in a help desk or call center environment and almost always have a unique reference number, also known as a case, issue or call log number which is used to allow the user or help staff to quickly locate, add to or communicate the status of the user's issue or request.
These tickets are so called because of their origin as small cards within a traditional wall mounted work planning system when this kind of support started. Operators or staff receiving a call or query from a user would fill out a small card with the user's details and a brief summary of the request and place it into a position (usually the last) in a column of pending slots for an appropriate engineer, so determining the staff member who would deal with the query and the priority of the request." [Issue tracking system. Wikipedia]
The UML activity diagram example "Ticket processing system" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Rapid UML solution from the Software Development area of ConceptDraw Solution Park.