# 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