The function f(x) seems to be selective for words or concepts related to the natural sciences (such as astronomy, biology, and chemistry) and general fields of study (such as mathematics and philosophy). It also shows some selectivity for concepts related to the environment (e.g., ocean). The function assigns higher values to these concepts, with values generally ranging from 0.01 to 0.05. In contrast, it assigns lower values (closer to 0) to words or concepts not related to these categories.