The use of AND’s and OR’s together in a single expression introduces ambiguity.

 

I will eat at a restaurant if “they serve pancakes” OR “they serve waffles” OR “they serve omelets” AND “the food is good quality” AND “the servers are friendly” AND “the cost is under $10”.

 

One way to interpret this is that I want: (1) either pancakes, waffles, or omelets (any of these) AND (2) quality food and friendly service at reasonable prices (all of these).  But is that how the system will interpret it?  No.

 

The interpretation a system will apply could trigger the action (me eating at a restaurant) as long as they serve pancakes.  See the expression with parenthesis clarifying how the expression is evaluated by the system:

 

I will eat at a restaurant if (“they serve pancakes”) OR (“they serve waffles”) OR (“they serve omelets” AND “the food is good quality” AND “the servers are friendly” AND “the cost is under $10”).

 

The difference is significant.  To correct this, the expression should be written as follows:

 

I will eat at a restaurant if (“they serve pancakes” OR “they serve waffles” OR “they serve omelets”) AND (“the food is hot” AND “the servers are friendly” AND “the cost is under $10”).*

 

*The second set of parenthesis isn’t actually required by the system.  However, inserting the additional parenthesis groups the statements together logically - making the rule easier to read.

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