Prueba de Hipótesis

Altogether, we identified eight classes of advertisements. We describe and depict these classes in the following. Our goals when developing these adver- tisement classes were to cover a wide range of possible offerings from publishers and to be consistent with the subscription classes identified before. That is, there should exist some overlap (see Section 2.1, page 11) between instances of these advertisement classes and instances of subscription classes.

Definition of Advertisement Class 1

We depict Advertisement Class 1 in Figure 3.4. Publishers conforming to this class are described as follows:

Advertisement Class 1 A publisher offers books of a particular category. These books are sold for a fixed price (Buy-It-Now item) that is greater than a certain minimal value. The publisher additionally offers signed book copies, also stating a minimal price.

BuyItNow = yes OR AND (book) Author = A AND Price > B AND

Price > C Attribute = signed

p1

p3

p2 p4 p5

Figure 3.5: Advertisement Class 2 including three variable predicates (p1, p3,

and p4).

Instances of this class contain three variable predicates, p1, p3, and p4. An

example assignment for these predicates is Category = Poetry for p1, Price

> 15.00for p3, and Price > 50.00 for p4 (example advertisement a1). A pub-

lisher specifying these predicates would thus sell books classified as “Poetry” for either a fixed price of more than NZ$15.00 or for more than NZ$50.00 for a signed copy.

Definition of Advertisement Class 2

Advertisement Class 2 is similar to Class 1 and illustrated in Figure 3.5. This class describes the following offering from a publishers:

Advertisement Class 2 A publisher is specialized in books of a particular author. She has a range of signed book copies and offers them in online auctions starting with a predefined minimal price. She also wants to sell books for a fixed price (Buy-It-Now items) above a certain threshold. Similar to Advertisement Class 1, there exist three variable predicates in Ad- vertisement Class 2: p1, p3, and p4. An exemplary instance could define these

predicates as follows: Author = “JK Rowling” for p1, Price > 20.00 for p3,

and Price > 100.00 for p4 (example advertisement a2). This instance of Ad-

vertisement Class 2 describes a publisher who specializes in books from “JK Rowling”. The books can be bought for a fixed price of more than NZ$20.00 (depending on the book). Signed books are sold to the highest bidder and have a starting price of NZ$100.00.

Definition of Advertisement Class 3

Advertisement Class 3 is visualized in Figure 3.6. Publishers specifying in- stances of this class could be characterized as follows:

Condition = new OR AND (book) Title = A AND AND Price > C Price > B Condition = used p1 p2 p3 p4 p5

Figure 3.6: Advertisement Class 3 including three variable predicates (p1, p3,

and p4). Format = hardcover OR AND (book) Title = A AND Price > B AND

Price > C Format = softcover

p1

p3

p2 p4 p5

Figure 3.7: Advertisement Class 4 including three variable predicates (p1, p3,

and p4).

Advertisement Class 3 A wholesaler has got a stock of books of the same title. Some of these books are slightly damaged and are thus sold as used items. These books are offered for a lower minimum price than the undamaged (i.e., new) items.

Advertisement Class 3 also contains three variable predicates: p1, p3, and p4. A

particular publisher could specify these predicates as follows: Title = “Harry Potter and the Goblet of Fire” for p1, Price > 11.00 for p3, and Price

> 14.00for p4(example advertisement a3). This publisher would have on offer

the fourth part of the “Harry Potter” book series for more than NZ$11.00 for a used book copy and more than NZ$14.00 for a new book.

Definition of Advertisement Class 4

Advertisement Class 4 is similar to Class 3, but states varying prices according to the book format instead of the condition of the book copy. It is shown in Figure 3.7 and could be defined as follows:

Advertisement Class 4 A book shop is selling the remainder of its stock of a certain book title via an online auction. The shop owner wants to earn

Title = A

Format = hardcover

Price > B

Condition = new Price > C Condition = used

AND Format = softcover OR Condition = used Price > E Price > D Condition = new AND AND AND OR AND AND OR AND (book) p10 p11 p8 p9 p3 p2 p6 p7 p4 p5 p1

Figure 3.8: Advertisement Class 5 including five variable predicates (p1, p5,

p6, p9, and p10).

at least a particular minimum price according to the format of the book copy. There are hardcover and softcover versions of the book.

There again exist three variable predicates in instances of Advertisement Class 4. They are p1, p3, and p4, and specify book title and minimal prices. An ex-

ample instance could specify Title = “Harry Potter and the Half-Blood Prince” for p1, Price > 30.00 for p3, and Price > 20.00 for p4 (example

advertisement a4). This publisher thus offers the sixth part of the “Harry Pot-

ter” series for more than NZ$20.00 for a softcover version and for more than NZ$30.00 for a hardcover version.

Definition of Advertisement Class 5

Advertisement Class 5 combines the two previous classes of advertisements. We graphically illustrate this class in Figure 3.8. Its textual description is as follows:

Advertisement Class 5 A new edition of an academic book has been pub- lished. The campus book shop (which is also selling used copies) decides to have a sellout of its large stock of this book. The shop owner wants to use an online auction for the sellout and specifies different minimal prices for softcover and hardcover versions of the book. Additionally, these minimal prices differ for new and used book copies.

Due to the extended specification of this advertisement class, its instances contain five variable predicates: p1, p5, p6, p9, and p10. We here refrain from

(book) OR

AND

Condition = used Price > A

AND

Condition = new Price > B

p1 p2 p3 p4

Figure 3.9: Advertisement Class 6 including two variable predicates p2 and

p3.

OR (book)

AND

Format = hardcover Price > A

AND

Format = softcover Price > B

p2 p3 p4

p1

Figure 3.10: Advertisement Class 7 including two variable predicates (p2 and

p3).

giving an example of an instance of this class. Predicate p6 should specify a

lower price than p5 and predicate p10 a lower price than p9.

Definition of Advertisement Classes 6 to 8

Our three remaining advertisement classes, Advertisement Classes 6 to 8, are more general versions of Advertisement Classes 3 to 5. We depict Classes 6 to 8 in Figures 3.9 to 3.11. Their descriptions are as follows:

Advertisement Class 6 A publisher offers a broad range of books. She only wants to sell these books if buyers want to pay more than a certain minimal price. This minimal price varies for new and used book copies. Advertisement Class 7 A book shop has an occasional sellout of various books. The shop owner wants to earn a different minimum amount of money, which only depends on the format of the book.

Advertisement Class 8 To sell a variety of books, a book shop is using an online auctioning system. The minimum prices of the offered books always depend on both the format (hardcover and softcover) and the condition (new and used) of a book.

Advertisement Class 6 (Figure 3.9) and Advertisement Class 7 (Figure 3.10) contain two variable predicates, p2 and p3. There are four variable predicates

OR (book)

Format = hardcover

Price > A

Condition = new Price > B Condition = usedCondition = newPrice > CPrice > DCondition = used

Format = softcover OR AND AND AND AND OR AND AND p2 p6 p1 p5 p4 p3 p7 p8 p9 p10

Figure 3.11: Advertisement Class 8 including four variable predicates (p4,

p5, p8, and p9).

for instances of Advertisement Class 8 (Figure 3.11): p4, p5, p8, and p9. For

examples of these classes, we refer to those given for Advertisement Classes 3 to 5 (obviously without the respective predicate on Title).