Changes

==Document history==

==Document history==

Portions of the above article were adapted from the following sources under the [[GNU Free Documentation License]], under other applicable licenses, or by permission of the copyright holders.

Portions of the above article are adapted from the following sources under the [[GNU Free Documentation License]], under other applicable licenses, or by permission of the copyright holders.

* [http://planetmath.org/encyclopedia/LogicalImplication.html "Logical implication"], [http://planetmath.org/ PlanetMath].

* [http://planetmath.org/encyclopedia/LogicalImplication.html "Logical implication"], [http://planetmath.org/ PlanetMath].