Research On Possibility Construction Space Theory And Computer Composition Thinking Model

Computer music is a multi-discipline. It focus'on obtaining music materials, setting and constructing musical parameters, delivering music and disseminating it by using of computer technology in music's composing and making. Among them, computer composition is the most interesting research field. Exploring this issue by the methods of computer science, artificial intelligence and creative thinking can bring a new ideal and greatly enrich the existing music compositional theory. Meanwhile, this can also promote the development of thinking science, artificial intelligence and other related subjects.The hierarchical structure of the musical language features are analyzed based on the ideas and concepts of musical shape analysis. The variation thinking and its characteristics, a kind of widespread imagery thinking, are explored during the composing, based on a model of creative thinking—Possibility Construction Space Theory(PCST). Variation operator set (VM*) is constructed at the musical melody level. Then, variation operator set V* in PCST is also constructed. This work can enrich and develop PCST.By generalizing main features of several algorithmic composition ways and the existence of the key problems in this field, a computer composition thinking model based on PCST is built. The significance of the thinking model in computer composition area is illustrated. And a completely creative thinking process is showed as an example of Yunnan folk songs.The main content can be summarized as follows:The basic elements of musical language, musical theories based on analysis and compositional basic theories and techniques are detailed introduced. Comparing the features of the music language and sound language or writing language, the hierarchical structure characteristics of music knowledge expression are explored. These results are directly constituted the basic elements in PCS and works as a musical knowledge process model.The compositional music process is probed from the Point of view of musical analysis. Using the theoretical model of motif-thematic initiated by Rudolph Reti (1885-1957), it is analyzed that how to compose musical works (such as Chinese Folk Songs) from the motif, the smallest structural unit in music, to develop the process and eventually produce music woks. The findings enrich the present computer composition theories, and also give us some advices on how to study in thinking science.The variation thinking characteristics are detailed analyzed in music composition. The results show that musical thinking ways at different levels have obvious characteristics of the variation thinking, including melodic thinking, rhythm thinking, harmony thinking, musical form thinking and emotional thinking. By variation the musical motifs at the micro-structure level, such as melody, rhythm, etc, lots of motif variant can be formed in music which are called musical sentences. Then, these musical materials can be composed as a certain style musical works by combining and varying musical sentences or even musical phrase at the macro-structure level. Furthermore, Variation operator set VM* is constructed at the musical main melody level. And variation operator set V* in PCST is also proposed. These works can enrich and prompt PCS theory.Based on hierarchical structure characteristics in musical language, the model of musical knowledge processing and analyzing the characteristics of variation thinking in music, three concepts of the character space are proposed according to the creative thinking model. They are the character space of musical motifs Sdj, the character space of musical motif variant Sbt, and the character space of musical form and style Sqs respectively.The definition is as follows: Sdj={Sds,Syc,Ssz,Shx,Sld, Sqg} Sbt＝{Sy,Sj,Syj} Sqs={Sds,Sqs,Sqg,Sfg}Finally, a simple creative thinking process for music composing system is established. On the basis of PCST and selection models, attribute set, rule set and variation operators in music, a simple creative thinking process for music composing operation is also introduced. An example is also discussed. This gives a possible way for scientifically describing the characters and effect of music composition.