Changes

A) '''Saturated Invention Spaces:''' The earliest definition of a patent thicket that we found is in Teece (1998), who points out a simple issue with patents. We refer to this as ‘saturated invention spaces’ and describe it as when a single firm, or a small number of firms, successfully patents an entire technological area. (p.15)

B) '''Diversely-held Complimentary Inputs (DHCI):''' 1) products require complementary patented inputs; 2) these inputs are diversely-held (i.e. held by N patent-holders); and 3) patent-holders set their license prices independently. (Shapiro, pg.17)

C) '''Overlapping Patents:'''

#The second most common foundation for a patent thicket issue relies on overlapping patents. Patent overlaps can be horizontal (i.e. though patents that are largely adjacent to one another) or vertical (i.e. when patents are related through cumulative innovation). Horizontal overlaps arise because patent rights are imperfectly defined property rights. (p.20)

#Refinement patents and research tool patents could result in vertically overlapping patent rights (or at least contractual rights). (p.21)

D) '''Gaming the Patent System:''' There are information asymmetries between a patent applicant and the patent office and a patent applicant may take some inappropriate action, for example by applying for a patent that is not novel or is obvious. Such an inappropriate action can impose costs on the patent office and may generate negative externalities, imposing costs on genuine innovators. We refer to this situation as ‘gaming the patent system’. (p.21)