Ranking function is a predictive algorithm that is used to establish a simple ordering of documents according to its relevance. This step is critical because the results’ quality of a Domain Specific Information Retrieval (IR) such as Hadith Information Retrieval is fundamentally dependent of the ranking function. A Hierarchical Fuzzy Logic Controller of Mamdani-type Fuzzy Inference System has been built to define the ranking function, based on the Malay Information retrieval’s BM25 Model. The model examines three-inputs (Ontology BM25 Score, Fabrication Rate of Hadith and Shia Rate of Hadith) and four-output values of Final Ranking Score which consist of three triangular membership functions. The proposed system has outperformed the BM25 original score and the Vector Space Model (VM) on 16 queries, while the BM25 original score and Vector Space Model only yield better result in 9 and 2 queries respectively on the P@10, %no measures and MAP. P@10 represent the values of Precision at Rank 10 P@10), %no measures represent the percentage of queries with no relevant documents in the top ten retrieved and MAP represents Mean Average Precision of the queries. The results show the proposed system have capability to demote negative documents and move up the relevant documents in the ranking list and its capability to recall unseen document with the application of ontology in text retrieval. For the future works, the researcher would like to apply the usage of other Malay Semantic elements and another corpus for positive ranking indicator.

The ranking function is a predictive algorithm that is used to establish a simple ordering of documents according to its relevance. This step is critical because the results’ quality of an IR System is fundamentally dependent on the ranking. This paper aims to develop the Fuzzy Logic Controller of Mamdani-type Fuzzy Inference System to define the ranking function, based on the Malay Information retrieval’s BM25 Model. The logic controller also includes Fabricated and Shia Malay Translated Hadith as the negative ranking indicator to demote the negative document to the bottom of the ranking retrieval results. The results then are evaluated by referring to the relevant documents issued by the Hadith experts and compared with the results produced by the BM25 model original score and the Vector Space Model. Based on the experiment’s result and evaluation, the proposed system has slightly outperformed the BM25 original score and the Vector Space Model (VM) on 11 queries, while the BM25 original score and Vector Space Model only yield a better result in five and eight queries respectively on the P@10, %no measures and MAP. Hence, proven the proposed system has a potential for further research to be conducted on these domains. Keywords: fuzzy logic; Malay text corpus; Malay translated hadith; fabricated and Shia hadith; BM25 negative ranking indicator