This paper examines irreversible investment in a project with uncertain returns, when there is an advantage to being the first to invest, and externalities to investing when others also do so. Pre-emption decreases and may even eliminate the option values created by irreversibility and uncertainty. Externalities introduce inefficiencies in investment decisions. Pre-emption and externalities com...

We prove that it is consistent that there is a non-reflexive Whitehead group, in fact one whose dual group is free. We also prove that it is consistent that there is a group A such that Ext(A,Z) is torsion and Hom(A,Z) = 0. As an application we show the consistency of the existence of new co-Moore spaces.

Want to launch a virtual enterprise using the Web as your technology infrastructure? First learn what's missing from today's Web architecture and which extensions are needed for large-scale collaboration. T he WorldWide Web connects islands of information, along with the people seeking that information, from within corporate intranets and across the global Internet, easily and effectively. Shar...

I referred her to [2], where Theorem 3.6 asserts that K1(R) is R /Ẽ, where Ẽ is the group generated by (1 + xy)/(1 + yx) with x, y in R and 1 + xy in R and where the last sentence in §3 says that Ẽ is not [R, R] in the case when R = M2(Z/2Z) is the ring of 2 by 2 matrices over a field of two elements (Z is the ring of integers). Moreover, in this case the group K1(R) is trivial while R/[R , R] ...

We review the interpretation of Whitehead products in homotopy theory as an entanglement topological defects ordered media.

We construct a smash product operation on secondary homotopy groups yielding the structure of a lax symmetric monoidal functor. Applications on cup-one products, Toda brackets and Whitehead products are considered.

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