Patent ID: 7518514

Claim:
A method for detecting the presence and absence of objects amongst at least two objects comprising: a) providing a plurality of tags, each tag for attachment on a corresponding object of said at least two objects, each tag having a wireless communication device and a unique identifier, b) providing a rule table storing at least one rule relative to the presence or absence of said objects according to the tag identifiers of said tags attached to said at least two objects, said at least one rule having the presence of one of said at least two objects as condition and the presence or absence of the other one of said at least two objects as consequence; c) providing an object table having tag entries for recording object and corresponding tag identifier data, wherein a tag entry comprises at least one virtual object representing a logical combination of said at least two objects; d) receiving a list of identifiers of detected tags; e) selecting as a current rule, a rule from said rule table; f) from said received list of identifiers of detected tags, determining if said current rule is applicable and in compliance, and if said current rule is not in compliance, generating a warning for a user; and, g) determining if said current rule is a last rule of said rule table and, if said current rule is not the last rule of said rule table, h) selecting the next rule of said rule table as the current rule; and, i) repeating steps f)-h) until said current rule is said last rule.