Information sharing system, communication apparatus, control method and computer program

A communication device that wirelessly transmits notification messages that comprise a first summary vector identifying content held by the communication device with other communication devices to communicate with them without going through an access point, comprising:

• an internal deduction portion that, based on a reception history comprising a log of notification messages received in additional summary vectors from each of the other communication devices, deduces which information has been notified to neighboring communication devices based on the reception history of at least two communication devices including the neighboring communication devices;
• a duplication determination portion that determines whether or not the information that has been notified by said other communication device deduced by the internal deduction portion matches information held by an own communication device;
• and
• an information exchange portion that, based on a determination that the information does not match, transmits a notification message that contains the information currently held by said own communication device that is different from the information that has been notified by said other communication devices deduced by the internal deduction portion.

A control method for controlling a communication device that wirelessly transmits notification messages that comprise a first summary vector identifying content held by the communication device with other communication devices to communicate with them without going through an access point, comprising:

• an internal deduction step of, based on a reception history comprising a log of notification messages received in additional summary vectors from each of said other communication devices, deducing which information has been notified to neighboring communication devices based on the reception history of at least two communication devices including the neighboring communication devices;
• a duplication determination step of determining whether or not the information that has been notified by other communication device deduced by the internal deduction portion matches information held by an own communication device;
• and
• an information exchange step of, based on a determination that the information does not match, transmitting a notification message containing the information currently held by said own communication device that is different from the information that has been notified by said other communication devices deduced by the internal deduction step.

A computer program that is stored on a computer-readable non-transitory recording medium of a communication device that wirelessly transmits notification messages that comprise a first summary vector identifying content held by the communication device with other communication devices to communicate with them without going through an access point, comprising:

• an internal deduction instruction for, based on a reception history comprising a log of notification messages received in additional summary vectors from each of said other communication devices, deducing which information has been notified to neighboring communication devices based on the reception history of at least two communication devices including the neighboring communication devices;
• a duplication determination instruction for determining whether or not the information that has been notified by other communication device deduced by the internal deduction portion matches information held by an own communication device;
• and
• an information exchange instruction, based on a determination that the information does not match, for transmitting a notification message containing the information currently held by said own communication device that is different from the information that has been notified by said other communication devices deduced by the internal deduction instruction.