How do you evaluate a logical statement that has multiple condition clauses "If A or B and C"? From method 1 & 2 below, which is the correct/common interpretation?
- If A is true, or both of B and C are true, then the statement is true.
- If either of A and B is true, and also if C is true, then the statement is true.
Using parentheses, the method 1 & 2 would be:
- A or (B and C)
- (A or B) and C
Coming from a programmer point of view, most programming languages use the method 1, where all 'and' are evaluated first before the 'or' are evaluated. Is it also true for English language in general usage?
To use a concrete example, consider the following A, B, C:
If it is morning or it is evening and it is Monday, then I will bring an umbrella.
Do I bring an umbrella if it is Tuesday morning?
Let me add additional information why I insist on not adding additional commas to resolve the ambiguity.
I'm designing a system where a non-technical user can define rules using English language with specific formats, for example:
- today is sunday
- date is 1st of june
- user's age is not less than 18
And the rules can be combined using "and" and "or":
today is sunday or date is 1st of june and user's age is not less than 18
Can I rely on a common interpretation in English using a well-known precedence of "and" and "or", or do I have to either:
- introduce commas into the rule grammar
- put a disclaimer on how the "and" and "or" will be interpreted by the system?