Inappropriate use will result in retrieving a lot of irrelevant material. Most will NOT allow truncation at the beginning of a word. BUT NOT containing the second word. This helps to eliminate unwanted material. For Boolean searching with FirstSearch, use the Advanced option which provides a form.
PALS assumes an AND between words.
This process works something like a complex mathematical formula. Finally, the search engine will return all records having at least one word from each of the three groups. The PALS systems does not have an adjacency feature. The PALS search engine looks for the given words any place in the record. The FirstSearch system assumes a Boolean AND between words.