If a data warehouse is based on the Kimball model, it is a dimensional schema. In a UNIVERSE built on that DW, for a FAN trap to occur in such a schema, we require DIRECT join between two fact TABLES, which is against the principles of dimensional MODELING.

On the other hand in a data warehouse based on Inmon model, it is a normalized schema. Though in such a case, universes are generally designed on Data Marts, which are dimensional schemas (where fan traps should not occur). However, if a universe is built on the DW (for the purpose of operational reporting), then a fan trap can occur in that universe.

If a data warehouse is based on the Kimball model, it is a dimensional schema. In a universe built on that DW, for a fan trap to occur in such a schema, we require direct join between two fact tables, which is against the principles of dimensional modeling.

On the other hand in a data warehouse based on Inmon model, it is a normalized schema. Though in such a case, universes are generally designed on Data Marts, which are dimensional schemas (where fan traps should not occur). However, if a universe is built on the DW (for the purpose of operational reporting), then a fan trap can occur in that universe.