A data flow-based information processing system, comprising: • at least one executive unit module adapted to output tokens containing at least a key and an operand; • at least one associative memory module adapted: - to receive a token; - to store a received token; - to search for at least one stored token with a received token by comparing the key of the stored tokens with the key of the received token; - to form a pair of operands from a received token and a stored token found with the received token; - to output the formed pair; and - to erase a stored token; • a second memory adapted to store tokens and to output stored tokens; • means for sending pairs output by the at least one associative memory module to the at least one executive unit module; • means for sending tokens output by the at least one executive unit module to the at least one associative memory module; • a control system (2f, 8) adapted: - to cause tokens output by the at least one executive unit module to be stored in the second memory; and - to cause tokens stored in the second memory to be sent to the at least one associative memory module; wherein: • the at least one associative memory module is adapted: - to store tokens containing a key comprising a plurality of bits which are set to logical values "0", "1" or "don't care"; and - to search a stored token with a received token by comparing the key of the stored tokens with the key of the received token wherein don't care bits of stored tokens are not determining in the comparison; • the control system (2f, 8) is adapted: - to provide a token containing a key with don't care bits; - to cause the at least one associative memory module to store the provided token; and - to cause a token received by the at least one associative memory module to be stored in the second memory in the case the provided token is found by the at least one associative memory module with the received token. • at least one executive unit module adapted to output tokens containing at least a key and an operand; • at least one associative memory module adapted: - to receive a token; - to store a received token; - to search for at least one stored token with a received token by comparing the key of the stored tokens with the key of the received token; - to form a pair of operands from a received token and a stored token found with the received token; - to output the formed pair; and - to erase a stored token; - to receive a token; - to store a received token; - to search for at least one stored token with a received token by comparing the key of the stored tokens with the key of the received token; - to form a pair of operands from a received token and a stored token found with the received token; - to output the formed pair; and - to erase a stored token; • a second memory adapted to store tokens and to output stored tokens; • means for sending pairs output by the at least one associative memory module to the at least one executive unit module; • means for sending tokens output by the at least one executive unit module to the at least one associative memory module; • a control system (2f, 8) adapted: - to cause tokens output by the at least one executive unit module to be stored in the second memory; and - to cause tokens stored in the second memory to be sent to the at least one associative memory module; - to cause tokens output by the at least one executive unit module to be stored in the second memory; and - to cause tokens stored in the second memory to be sent to the at least one associative memory module; • the at least one associative memory module is adapted: - to store tokens containing a key comprising a plurality of bits which are set to logical values "0", "1" or "don't care"; and - to search a stored token with a received token by comparing the key of the stored tokens with the key of the received token wherein don't care bits of stored tokens are not determining in the comparison; - to store tokens containing a key comprising a plurality of bits which are set to logical values "0", "1" or "don't care"; and - to search a stored token with a received token by comparing the key of the stored tokens with the key of the received token wherein don't care bits of stored tokens are not determining in the comparison; • the control system (2f, 8) is adapted: - to provide a token containing a key with don't care bits; - to cause the at least one associative memory module to store the provided token; and - to cause a token received by the at least one associative memory module to be stored in the second memory in the case the provided token is found by the at least one associative memory module with the received token. - to provide a token containing a key with don't care bits; - to cause the at least one associative memory module to store the provided token; and - to cause a token received by the at least one associative memory module to be stored in the second memory in the case the provided token is found by the at least one associative memory module with the received token.