# Which Operators Accept Weights

Weights are used in conjunction with operators to compute scores for parent and child topics during a search. The weight you assign to a topic child can be a number between 0.01 and 1.00. A child’s weight indicates its importance relative to the other children that have been defined for its parent. The higher a child’s weight, the more important that child is considered to be with respect to its siblings.

Weights can only be assigned to the children of topics which use the concept operators, as follows:

• AND

• OR

• ACCRUE

Topics which use the proximity operators SENTENCE and PARAGRAPH, cannot be assigned a weight. These operators assume a simple "yes" or "no" presence for their children.

Note that if a topic assigned a proximity operator is, in turn, the child of a topic which has been assigned a concept operator, such as the AND operator, that child can be assigned a weight.

It is not mandatory that you assign weights to the children of a topic just because the operator can accept weighted children. When weights are not assigned, the child has an automatic weight assignment based on its operator. Children of topics using AND and OR operators assume a weight of 1.00, and children of topics using the ACCRUE operator assume a weight of 0.50. If these operators are changed-for example, if an OR operator is changed to an ACCRUE operator-the weights of children which have not been specifically assigned a weight change accordingly. Thus, if an unweighted child of an AND topic has an assumed weight of 1.00, this assumed weight changes to 0.50 if the operator is changed to ACCRUE.

If you assign a variable weight to a topic child, then change the operator used with the parent to one which does not accept weighted children, such as the SENTENCE operator. The Verity search engine will automatically assume a weight of 1.00 while this operator is in effect. If the operator is subsequently changed to one which accepts variable-weighted children, the previously-assigned variable weights will become effective once again.