Cactus Language • Semantics 5

Last time we reached the threshold of a potential codomain or target space for the kind of semantic function we need at this point, one able to supply logical meanings for the syntactic strings and graphs of a given cactus language.  In that pursuit we came to contemplate the following definitions.

Logical Conjunction
The conjunction \mathrm{Conj}_j^J q_j of a set of propositions \{ q_j : j \in J \} is a proposition which is true if and only if every one of the q_j is true.

\mathrm{Conj}_j^J q_j is true  \Leftrightarrow  q_j is true for every j \in J.

Logical Surjunction
The surjunction \mathrm{Surj}_j^J q_j of a set of propositions \{ q_j : j \in J \} is a proposition which is true if and only if exactly one of the q_j is untrue.

\mathrm{Surj}_j^J q_j is true  \Leftrightarrow  q_j is untrue for unique j \in J.

If the set of propositions \{ q_j : j \in J \} is finite then the logical conjunction and logical surjunction can be represented by means of sentential connectives, incorporating the sentences which represent the propositions into finite strings of symbols.

If J is finite, for instance, if J consists of the integers in the interval j = 1 ~\text{to}~ k, and if each proposition q_j is represented by a sentence s_j, then the following forms of expression are possible.

Logical Conjunction
The conjunction \mathrm{Conj}_j^J q_j can be represented by a sentence which is constructed by concatenating the s_j in the following fashion.

\mathrm{Conj}_j^J q_j ~\leftrightsquigarrow~ s_1 s_2 \ldots s_k.

Logical Surjunction
The surjunction \mathrm{Surj}_j^J q_j can be represented by a sentence which is constructed by surcatenating the s_j in the following fashion.

\mathrm{Surj}_j^J q_j ~\leftrightsquigarrow~ \texttt{(} s_1 \texttt{,} s_2 \texttt{,} \ldots \texttt{,} s_k \texttt{)}.

If one opts for a mode of interpretation which moves more directly from the parse graph of a sentence to the potential logical meaning of both the PARC and the PARCE then the following specifications are in order.

A cactus graph rooted at a particular node is taken to represent what that node represents, namely, its logical denotation.

Denotation of a Node
The logical denotation of a node is the logical conjunction of that node’s arguments, which are defined as the logical denotations of that node’s attachments.
The logical denotation of either a blank symbol or empty node is the boolean value \underline{1} = \mathrm{true}.
The logical denotation of the paint \mathfrak{p}_j is the proposition p_j, a proposition regarded as primitive, at least, with respect to the level of analysis represented in the current instance of \mathfrak{C} (\mathfrak{P}).
Denotation of a Lobe
The logical denotation of a lobe is the logical surjunction of that lobe’s arguments, which are defined as the logical denotations of that lobe’s appendants.
As a corollary, the logical denotation of the parse graph of \texttt{()}, also known as a needle, is the boolean value \underline{0} = \mathrm{false}.

Resources

cc: Academia.edu • BlueSky • Laws of FormMathstodonResearch Gate
cc: Conceptual Graphs • CyberneticsStructural ModelingSystems Science

This entry was posted in Automata, Boolean Algebra, Boolean Functions, C.S. Peirce, Cactus Graphs, Differential Logic, Equational Inference, Formal Grammars, Formal Languages, Graph Theory, Logic, Logical Graphs, Mathematics, Minimal Negation Operators, Painted Cacti, Propositional Calculus, Visualization and tagged , , , , , , , , , , , , , , , , . Bookmark the permalink.

2 Responses to Cactus Language • Semantics 5

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