2. The language understanding apparatus according to claim 1 , further comprising an access table generator that receives the input utterance data, performs parsing of the utterance content indicated by the received input utterance data to acquire a dependency relationship among morpheme sequences constituting the utterance content, and generates access table data indicating an accessibility among the morpheme sequences based on the acquired dependency relationship, wherein when making a bid for each semantic frame, the bidding section specifies, from the concept representation detected by the phrase interpreter, a concept representation corresponding to a concept corresponding to each variable of the semantic frame or a subordinate concept of that concept, and a concept representation whose variable of another semantic frame is not bidden, and bids the variable for the specified concept representation when the access table data generated by the access table generator indicates that the concept representation corresponding to the semantic frame is accessible to the specified concept representation.
2. The language understanding apparatus according to claim 1 , further comprising an access table generator that receives the input utterance data, performs parsing of the utterance content indicated by the received input utterance data to acquire a dependency relationship among morpheme sequences constituting the utterance content, and generates access table data indicating an accessibility among the morpheme sequences based on the acquired dependency relationship, wherein when making a bid for each semantic frame, the bidding section specifies, from the concept representation detected by the phrase interpreter, a concept representation corresponding to a concept corresponding to each variable of the semantic frame or a subordinate concept of that concept, and a concept representation whose variable of another semantic frame is not bidden, and bids the variable for the specified concept representation when the access table data generated by the access table generator indicates that the concept representation corresponding to the semantic frame is accessible to the specified concept representation. 3. The language understanding apparatus according to claim 2 , wherein the access table generator separates or combines the morpheme sequences in such a way that one of the morpheme sequences undergone the parsing includes one parsed concept representation detected by the phrase interpreter, and generates the access table data using a resultant morpheme sequence.