# zeroth order logic

calculus \PMlinkescapephraseCalculus \PMlinkescapephrasecolumn \PMlinkescapephraseColumn \PMlinkescapephrasecolumns \PMlinkescapephraseColumns \PMlinkescapephrasecompact \PMlinkescapephraseCompact \PMlinkescapephrasedegree \PMlinkescapephraseDegree \PMlinkescapephraseformal logic  \PMlinkescapephraseFormal logic \PMlinkescapephraselevel \PMlinkescapephraseLevel \PMlinkescapephraseorder \PMlinkescapephraseOrder \PMlinkescapephrasereference \PMlinkescapephraseReference \PMlinkescapephrasetranslation \PMlinkescapephraseTranslation

## 1 Propositional forms

 Table 1. Propositional Forms on One Variable $\mathcal{L}_{1}$ $\mathcal{L}_{2}$ $\mathcal{L}_{3}$ $\mathcal{L}_{4}$ $\mathcal{L}_{5}$ $\mathcal{L}_{6}$ $x=$ 1 0 $f_{0}$ $f_{00}$ 0 0 $()$ false $0$ $f_{1}$ $f_{01}$ 0 1 $(x)$ not $x$ $\lnot x$ $f_{2}$ $f_{10}$ 1 0 $x$ $x$ $x$ $f_{3}$ $f_{11}$ 1 1 $(())$ true $1$

Table 2 lists equivalent expressions for the sixteen functions of concrete type $X\times Y\to\mathbb{B}$ and abstract type $\mathbb{B}\times\mathbb{B}\to\mathbb{B}$ in the same set of languages.

 Table 2. Propositional Forms on Two Variables $\mathcal{L}_{1}$ $\mathcal{L}_{2}$ $\mathcal{L}_{3}$ $\mathcal{L}_{4}$ $\mathcal{L}_{5}$ $\mathcal{L}_{6}$ $x=$ 1 1 0 0 $y=$ 1 0 1 0 $f_{0}$ $f_{0000}$ 0 0 0 0 $()$ false $0$ $f_{1}$ $f_{0001}$ 0 0 0 1 $(x)(y)$ neither $x$ nor $y$ $\lnot x\land\lnot y$ $f_{2}$ $f_{0010}$ 0 0 1 0 $(x)y$ $y$ and not $x$ $\lnot x\land y$ $f_{3}$ $f_{0011}$ 0 0 1 1 $(x)$ not $x$ $\lnot x$ $f_{4}$ $f_{0100}$ 0 1 0 0 $x(y)$ $x$ and not $y$ $x\land\lnot y$ $f_{5}$ $f_{0101}$ 0 1 0 1 $(y)$ not $y$ $\lnot y$ $f_{6}$ $f_{0110}$ 0 1 1 0 $(x,y)$ $x$ not equal to $y$ $x\neq y$ $f_{7}$ $f_{0111}$ 0 1 1 1 $(xy)$ not both $x$ and $y$ $\lnot x\lor\lnot y$ $f_{8}$ $f_{1000}$ 1 0 0 0 $xy$ $x$ and $y$ $x\land y$ $f_{9}$ $f_{1001}$ 1 0 0 1 $((x,y))$ $x$ equal to $y$ $x=y$ $f_{10}$ $f_{1010}$ 1 0 1 0 $y$ $y$ $y$ $f_{11}$ $f_{1011}$ 1 0 1 1 $(x(y))$ not $x$ without $y$ $x\Rightarrow y$ $f_{12}$ $f_{1100}$ 1 1 0 0 $x$ $x$ $x$ $f_{13}$ $f_{1101}$ 1 1 0 1 $((x)y)$ not $y$ without $x$ $x\Leftarrow y$ $f_{14}$ $f_{1110}$ 1 1 1 0 $((x)(y))$ $x$ or $y$ $x\lor y$ $f_{15}$ $f_{1111}$ 1 1 1 1 $(())$ true $1$

The columns of Tables 1 and 2 are conveniently described in the following order:

• Language $\mathcal{L}_{3}$.

In Table 1, $\mathcal{L}_{3}$ describes each boolean function $f:\mathbb{B}\to\mathbb{B}$ by means of the sequence of two boolean values $(f(1),f(0))$.
In Table 2, $\mathcal{L}_{3}$ describes each boolean function $f:\mathbb{B}^{2}\to\mathbb{B}$ by means of the sequence of four boolean values $(f(1,1),f(1,0),f(0,1),f(0,0))$.
Sequences of these forms, perhaps in another order and perhaps with the logical values F and T instead of the boolean values 0 and 1, would normally be displayed vertically in a truth table  under the column head for $f$.

• Language $\mathcal{L}_{2}$ lists the functions in the form $f_{i}$, where the index $i$ is a bit string formed from the sequence of boolean values in $\mathcal{L}_{3}$.

• Language $\mathcal{L}_{1}$ notates the functions $f_{i}$ with an index $i$ that is the decimal equivalent of the binary numeral index in $\mathcal{L}_{2}$.

Notice that the sense of the binary and decimal codings is highly dependent on context. One needs to know the number of variables in the function and the sequence of points over which it is evaluated in order to decode the indices properly.

• Language $\mathcal{L}_{4}$ expresses the boolean functions in terms of two families of logical operations  :

$\begin{array}[]{ccc}xy&=&x\land y\\ xyz&=&x\land y\land z\\ \end{array}$

Minimal negation operators written as parenthesized lists. For example:

$\begin{array}[]{ccc}()&=&0\\ (x)&=&\lnot x\\ (x,y)&=&x\neq y\\ \end{array}$

• Language $\mathcal{L}_{5}$ lists ordinary language expressions for the propositional forms. Many other paraphrases are possible, but these afford a sample of the simplest equivalents.

• Language $\mathcal{L}_{6}$ expresses the propositional forms in one of the several notations that are commonly used in formal logic.

 Title zeroth order logic Canonical name ZerothOrderLogic Date of creation 2013-03-22 17:55:47 Last modified on 2013-03-22 17:55:47 Owner Jon Awbrey (15246) Last modified by Jon Awbrey (15246) Numerical id 19 Author Jon Awbrey (15246) Entry type Definition Classification msc 03G05 Classification msc 03B05 Related topic PropositionalCalculus Related topic LogicalConnective Related topic LogicalGraph Related topic LogicalGraphFormalDevelopment Related topic TruthFunction Related topic TruthTable Related topic DifferentialLogic Related topic DifferentialPropositionalCalculus Related topic DifferentialPropositionalCalculusAppendices Related topic DifferentialPropositionalCalculusAppendix2