<p>The rules seen in <a href="//commons.wikimedia.org/wiki/File:Logical_connectives_table.svg" title="File:Logical connectives table.svg">File:Logical connectives table.svg</a> and <a href="//commons.wikimedia.org/wiki/File:Logical_connectives_table_with_shorthands.svg" title="File:Logical connectives table with shorthands.svg">File:Logical connectives table with shorthands.svg</a> in condensed form
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The two squares are Cayley tables of the <a href="https://en.wikipedia.org/wiki/Klein_four-group" class="extiw" title="w:Klein four-group">Klein four-group</a>
<table><tbody><tr><td style="padding: 15px;"><a href="//commons.wikimedia.org/wiki/File:Watchduck.svg" class="image"><img alt="Watchduck.svg" src="https://upload.wikimedia.org/wikipedia/commons/thumb/d/d8/Watchduck.svg/40px-Watchduck.svg.png" decoding="async" width="40" height="46" srcset="https://upload.wikimedia.org/wikipedia/commons/thumb/d/d8/Watchduck.svg/60px-Watchduck.svg.png 1.5x, https://upload.wikimedia.org/wikipedia/commons/thumb/d/d8/Watchduck.svg/80px-Watchduck.svg.png 2x" data-file-width="703" data-file-height="806"></a>
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<td><a href="//commons.wikimedia.org/wiki/User:Watchduck" title="User:Watchduck">Watchduck</a><br><span style="color: gray; font-size: 80%;">You can name the author as "T. Piesk", "Tilman Piesk" or "Watchduck".</span>
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<span class="int-own-work" lang="en">Own work</span>