Note that we assume so far that A does not participate in the mining process. In case A is a miner or compromises a node that participates in the mining process, then the advantage of A in mounting double-spending attacks on zero-confirmation transactions can further increase depending on the mining power available to the adversary.
Namely, Finney  describes a double-spending attack in Bitcoin where the attacker includes in his or her generated blocks a number of transactions that transfer some coins between his or her own addresses. These blocks are only released in the network after the attacker double-spends the same coins using zero-confirmation payments and acquires a given service.
Clearly, the success probability of this attack depends on the mining power available to the adversary. Given the tremendous computing power that supports the current Bitcoin network,  the success probability of an adversary that does not control a considerable fraction of the mining power is only negligible.
-  Here, “Location” denotes the location of V, “connections” denote the number of V’s connections.The success probability is adapted from the findings of  and is interpolated by means ofexperiments using Amazon nodes.
-  The hashing rate in Bitcoin amounted to 0.5-1016 hashes per second in November 2015.