Article 5V1X6 Linear logic arithmetic

Linear logic arithmetic

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John
from John D. Cook on (#5V1X6)

Linear logic has connectives not used in classical logic. The connectives and & are conjunctions, and are disjunctions, and ! and ? are analogous to the modal operators 25fb.png and (necessity and possibility).

linear_con_dis_add_mult.png

Another way to classify the connectives is to say and & are called additive, and are multiplicative, and ! and ? are called exponential.And still another classification says that , , and ! have positive polarity, while &, , and ? have negative polarity.

linear_pos_neg_add_mult_exp.png

This post will show that these arithmetical names are justified by analogy.

For one thing, multiplication-like connectives distribute over addition-like connectives.
2
linear_distributive_add_mult2.png

Also, the exponential-like operators behave analogously to the equation

expab.png

with respect to the addition-like and multiplication-like connectives.

linear_exponential_analogy.png

In both equations, if you apply an exponential-like operator to the result of applying an addition-like operator, you get a multiplication-like operator applied to the exponential-like operator applied to two addition-like arguments separately.

The term polarity" is justified by the fact that linear negation flips the polarity of connectives.

In the following analogs of De Morgan's laws, negation turns conjunctions into disjunctions and vice versa, and it reverses the polarity of connectives.

linear_demorgan.png

Negating exponential connectives also flips polarity.

linear_neg_exp.png

These rules are analogous to the rules for negating quantifiers in classical logic.

not_exists_forall.png

More logic postsThe post Linear logic arithmetic first appeared on John D. Cook.
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