24. A positioning or navigation system, comprising: a receiver configured to receive satellite carrier signals; and a computer system coupled to the receiver, the computer system including one or more processors and a memory coupled to the processor one or more processors, the memory storing one or more programs for resolving ambiguities associated with carrier phase measurements of at least some of the carrier signals received from satellites in an identified set of satellites, the one or more programs being configured for execution by the one or more processors and including: instructions for identifying a set of ambiguities associated with the carrier phase measurements; instructions for estimating integer ambiguities in the set of ambiguities, including determining a best candidate set and a second best candidate set of integer ambiguity values for each of ambiguities in the set of ambiguities; instructions for determining that the best candidate set of ambiguity values fail to meet a discrimination test with respect to the second best candidate set, and upon such determination, removing from the set of ambiguities each ambiguity for which integer ambiguity values in the best candidate set and second best candidate set fail to meet predefined criteria to produce a reduced set of ambiguities; instructions for performing operations to resolve the integer ambiguities in the reduced set of ambiguities; and instructions for generating a result in accordance with the resolved integer ambiguities in the reduced set of ambiguities.
31. The system of claim 24 , wherein the instructions for removing include instructions for removing from the set of ambiguities all the ambiguities for a satellite for which the integer ambiguity values in the best candidate set and second best candidate set fail to meet the predefined criteria.