# ambiguous written description of decision node of flow diagram

The picture shows a decision node in one of the embodiments of my software method in my patent application.

I gave this diagram to the attorney. The attorney wrote the description for this node as such:

This node is described in words as:

`"If A and/or B, then do X. If not A and/or not B, then do Y."`

This is logically ambiguous to me.

clear outcome:

1. A is true and B is true, then do X
2. A is false and B is false, then do Y

ambiguous outcome:

1. A is true and B is false, then doing either X or Y is valid
2. A is false and B is true, then doing either X or Y is also valid

Is this OK?

Or do I need to simplify this node?

• But the original phrasing is in fact: "If A and/or B, then do X. If not A and/or not B, then do Y." The ambiguity lies in using "and/or" Commented Aug 18 at 18:11
• Did you intend it to mean exclusive or? Is the flowchart as you presented it also in the drawings and does it matter to the invention to be exclusive or? Commented Aug 18 at 20:25
• Normally in a flowchart or means and/or. You would use exclusive or if both being true has resulting behavior of both being false. Commented Aug 18 at 20:49

In most computer languages I'm familiar with "OR" is inclusive. Thus

"If A and/or B, then do X. If not A and/or not B, then do Y." should mean:

1. If A is true then do X
2. If B is true then do X
3. If A is false and B is false then do Y

The problem is with the quoted statement is the second "and/or". This makes more sense:

"If A and/or B, then do X. If not A and not B, then do Y." Even simpler would be "If A and/or B, then do X else do Y"

If an exclusive or is provided in a language it usually has a different syntax like "XOR" in Python and "^" in Java.

• Indeed, it is the second "and/or" that is problematic and ambiguous. The patent application does explicitly define that "OR" should mean inclusive. Hence the correct statement should simply be `"If A or B, then do X. If not A and not B, then do Y."` Commented Aug 19 at 0:30

The specification must be written in English; the conventions of any particular programming language should be mostly irrelevant unless the specification is quoting parts of an attached computer program listing appendix or some such similar situation.

IMHO, the most idiomatic way to express that piece of the flowchart in English is:

``````If A or B then do X; otherwise do Y.
``````

One can change the "or" into "and/or" if there is concern that it may be ambiguous, in English, whether the "or" on its own is inclusive or not.

Note also that the logical "or" can be implemented in the flowchart directly by testing "A?" first and then "B?" on the branch where "A?" was false, and routing both of the true branches to X and the remaining "B?" false branch to Y.

(This raises the interesting question of whether such trivial rearrangements are considered equivalents when the function of whole flowchart is claimed using means-plus-function language).

In patent language the word "or" is a logical "xor", and the word "and/or" is a logical "or".

Your attorney only made a typo. It should be: "If A and/or B, then do X. If not A and not B, then do Y." And your figure should be adapted and instead of or your figure should say "and/or".

• I do not think you can flatly say “or means exclusive or” in all cases and contexts in patents. Commented Sep 4 at 4:06
• Can you provide a link proving that or is defined to be exclusive in patents? Commented Sep 7 at 0:46