Many times a Boolean equation quickly becomes large, complex, and even unmanageable. You need a way to manage this complexity while at the same time verifying that your logic works as designed.

To fix this situation, try applying the theorems shown in Table 3-1 to minimize these types of equations.

Table 3-1. Boolean theorems

Theorem ID |
Theorem definition |
---|---|

T0 |
!(!x) == x |

T1 |
x | x == x |

T2 |
x | !x == true |

T3 (DeMorgan’s Theorem) |
!x | !y == !(x & y) |

T4 |
x & x == x |

T5 |
x & !x == false |

T6 (DeMorgan’s Theorem) |
!x & !y == !(x | y) |

T7 (Commutative Law) |
x | y == y | x |

T8 (Associative Law) |
(x | y) | z == x | (y | z) |

T9 (Distributive Law) |
x & y | x & z == x & (y | z) |

T10 |
x | x & y = x |

T11 |
x & y | x & !y = x |

T12 |
(x & y) | (!x & z) | (y & z) == (x & y) | (!x & z) |

T13 (Commutative Law) |
x & y == y & x |

T14 (Associative Law) |
(x & y) & z == x & (y & z) |

T15 (Distributive Law) |
(x | y) & (x | z) == x | (y & z) |

T16 |
x & (x | y) = x |

T17 |
(x | y) & (x | !y) = x |

T18 |
(x | y) & (!x | z) & (y | z) == (x | y) & (!x | z) |

T19 |
x | x | x | ... | x == x |

T20 |
!(x | x | x | ... | x) == !x & !x & !x & ... & !x |

T21 |
x & x & x & ... & x == x |

T22 |
!(x & x & x & ... & x) == !x | !x | !x | ... | !x |

T23 |
(x | y) & (w | z) == (x & w) | (x * z) | (y & w) | (y * z) |

T24 |
(x & y) | (w & z) == (x | w) & (x | z) & (y | w) & (y | z) |

In Table 3-1, assume that `w`

,
`x`

, `y`

, and `z`

are all variables of type `bool`

. The
`Theorem`

`ID`

column ...

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