1) https://en.wikipedia.org/wiki/Reductio_ad_absurdum
2) XMPP is an open standard. The opposite of the gated community example.
3) There are various degrees of monopoly, and rarely does anything
approaching pure monopoly exist. Thus, the term is generally used in a
relative sense rather than an absolute one. For example, a company can still
be considered a monopoly even if it faces competition from (1) a few
relatively small scale suppliers of the same or similar product(s) or (2)
somewhat different goods or services that can to some limited extent be
substituted for the product(s) supplied by the monopolist. A business that
produces multiple products can be considered a monopoly even if it has a
monopoly with regard to only one of the products.
http://www.linfo.org/monopoly.html
That's the end of this on my side.
