# Principle of Non-Contradiction/Proof Rule/Technical Note

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## Technical Note on Principle of Non-Contradiction

When invoking the Principle of Non-Contradiction in a tableau proof, use the {{NonContradiction}} template:

{{NonContradiction|line|pool|first|second}}

or:

{{NonContradiction|line|pool|first|second|comment}}

where:

line is the number of the line on the tableau proof where the Principle of Non-Contradiction is to be invoked
pool is the pool of assumptions (comma-separated list)
first is the first of the two lines of the tableau proof upon which this line directly depends
second is the second of the two lines of the tableau proof upon which this line directly depends
comment is the (optional) comment that is to be displayed in the Notes column.