The minimal norm least squares Hermitian solution of the complex matrix equation AXB+CXD=E

In this paper, by applying the real representations of complex matrices, the particular structure of the real representations and the Moore–Penrose generalized inverse, we obtain the explicit expression of the minimal norm least squares Hermitian solution of the complex matrix equation $AXB+CXD=E$. And we also derive the minimal norm least squares Hermitian solution of the complex matrix equation $AXB=E$. Our proposed formulas only involve real matrices, and therefore are more effective and portable than those reported in Yuan and Liao (2014). The corresponding algorithms only perform real arithmetic which also consider the particular structure of the real representations of complex matrices. Two numerical examples are provided to demonstrate the effectiveness of our algorithms.     

When is an invention really radical?: Defining and measuring technological radicalness

We develop a valid definition of technological radicalness which states that a successful radical invention is: (1) novel; (2) unique; and (3) has an impact on future technology. The first two criteria allow us to identify potentially radical inventions ex ante market introduction; adding the third condition, we can ex post determine if an invention served as an important change agent. Empirically testable condition selected 6 of 581 tennis racket patents granted between 1971 and 2001. Two of the identified patents - the oversized and the wide-body rackets - are considered radical inventions by industry experts. Applying our definition and operationalization would allow researchers to achieve greater generalizability across studies, avoid endogenous definitions of radicalness, and study predictors of market success for radical inventions.     

How open is open enough?: Melding proprietary and open source platform strategies

Computer platforms provide an integrated architecture of hardware and software standards as a basis for developing complementary assets. The most successful platforms were owned by proprietary sponsors that controlled platform evolution and appropriated associated rewards.Responding to the Internet and open source systems, three traditional vendors of proprietary platforms experimented with hybrid strategies which attempted to combine the advantages of open source software while retaining control and differentiation. Such hybrid standards strategies reflect the competing imperatives for adoption and appropriability, and suggest the conditions under which such strategies may be preferable to either the purely open or purely proprietary alternatives.