In user relevance feedback which of the following is a disadvatage of probabilistic model the feedback process is directly related to the derivation of new weights for query terms document term weights are taken in to account during the feed backloop weights of terms in the previous query formulations are regarded No query expansion is used

The disadvantage of the probabilistic model in user relevance feedback is that "No query expansion is used".

Here's why:

1. In the probabilistic model, the feedback process is directly related to the derivation of new weights for query terms. This is not a disadvantage, but rather a feature of the model. It allows the model to adjust the importance of different terms based on user feedback.

2. Document term weights are taken into account during the feedback loop. This is also not a disadvantage. It means that the model considers the frequency of terms in the document collection when adjusting query term weights.

3. Weights of terms in the previous query formulations are regarded. This is also not a disadvantage. It allows the model to learn from past queries and improve future ones.

4. No query expansion is used. This is a disadvantage. Query expansion is a technique used to improve the effectiveness of information retrieval systems by considering synonyms, misspellings, and other variations of the query terms. Without query expansion, the probabilistic model may miss relevant documents that use different but related terms.