34. The system of claim 24 , the operations further comprising: determining that the search query is parent-like; and selecting only candidate refinement queries that are parent-like as being refinement queries for the search query.
35. The system of claim 34 , wherein determining that a particular query is parent-like includes: generating a modified query that semantically represents a grouping, where the grouping is related to a lexical item represented by the particular query; and determining that the particular query is parent-like when the modified query has a frequency of being submitted beyond a threshold value.