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Bisimulations are a broadly used formalism to define the semantics of process algebras. In particular, by means of weak bisimulation most of the internal activity of processes may be abstracted. Unfortunately, this is not fully accomplished: for instance, the internal choice operator becomes non-associative since bisimulation can see the branching structure of processes. In this paper we propose global timed bisimulation as a weakening of weak timed bisimulation. Global timed bisimulation is defined exactly as weak timed bisimulation once ordinary transitions are replaced by the adequate notions of generalized transitions. In order to asses the definition of our global timed bisimulation we present a collection of small examples that illustrate each of the clauses of that definition. Finally, a more elaborated example is presented to summarize the main properties of that notion.

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Many different types of auctions can be applied to determine selling prices, each of them fulfilling different properties. Among them, Vickrey auctions are specially interesting due to the fact that they disallow strategic behaviors of the bidders. In fact, the dominant strategy for each bidder consists in bidding his reserve price. However, somebody has to collect all the bids, so that bids are not kept private. In this paper we present a method to overcome this problem. That is, we present a way to implement Vickrey auctions preserving the privacy of all the bidders.