# Proof by Contradiction/Proof Rule/Technical Note

## Proof Rule

When invoking Proof by Contradiction in a tableau proof, use the Contradiction template:

{{Contradiction|line|pool|statement|start|end}}

where:

line is the number of the line on the tableau proof where the Proof by Contradiction is to be invoked
pool is the pool of assumptions (comma-separated list)
statement is the statement of logic that is to be displayed in the Formula column, without the $...$ delimiters
start is the start of the block of the tableau proof upon which this line directly depends
end is the end of the block of the tableau proof upon which this line directly depends