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[parent] example of polyadic algebra with equality (Example)

Recall that given a triple $ (A,I,X)$ where $ A$ is a Boolean algebra, $ I$ and $ X\neq \varnothing$ are sets. we can construct a polyadic algebra % latex2html id marker 249 $ (B,I,\exists,S)$ called the functional polyadic algebra for $ (A,I,X)$. In this entry, we will construct an example of a polyadic algebra with equality called the functional polyadic algebra with equality from % latex2html id marker 253 $ (B,I,\exists,S)$.

We start with a simpler structure. Let $ B$ be an arbitrary Boolean algebra, $ I$ and $ X\neq \varnothing$ are sets. Let $ Y=X^I$, the set of all $ I$-indexed $ X$-valued sequences, and $ Z=B^Y$, the set of all functions from $ Y$ to $ B$. Call the function $ e:I\times I\to Z$ the functional equality associated with $ (B,I,X)$, if for each $ i,j\in I$, $ e(i,j)$ is the function defined by

\begin{displaymath} % latex2html id marker 281e(i,j)(x):=\left\{ \begin{array}... ...rm{if }x_i=x_j, \ 0 & \textrm{otherwise.} \end{array}\right. \end{displaymath}
The quadruple $ (B,I,X,e)$ is called a functional equality algebra.

Now, $ B$ will have the additional structure of being a polyadic algebra. Start with a Boolean algebra $ A$, and let $ I$ and $ X$ be defined as in the last paragraph. Then, as stated above in the first paragraph, and illustrated in here, % latex2html id marker 293 $ (B,I,\exists,S)$ is a polyadic algebra (called the functional polyadic algebra for $ (A,I,X)$). Using the $ B$ just constructed, the quadruple $ (B,I,X,e)$ is a functional equality algebra, and is called the functional polyadic algebra with equality for $ (A,I,X)$.

It is not hard to show that $ e$ is an equality predicate on % latex2html id marker 305 $ C=(B,I,\exists,S)$, and as a result $ (C,e)$ is a polyadic algebra with equality.

Bibliography

1
P. Halmos, Algebraic Logic, Chelsea Publishing Co. New York (1962).



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Also defines:  functional equality algebra, functional equality, functional polyadic algebra with equality

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Cross-references: equality predicate, functions, sequences, structure, polyadic algebra with equality, functional polyadic algebra, polyadic algebra, Boolean algebra
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This is version 2 of example of polyadic algebra with equality, born on 2008-03-18, modified 2008-03-18.
Object id is 10417, canonical name is ExampleOfPolyadicAlgebraWithEquality.
Accessed 753 times total.

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AMS MSC03G15 (Mathematical logic and foundations :: Algebraic logic :: Cylindric and polyadic algebras; relation algebras)

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