Skip to main content

Through an Inference Rule, Darkly

  • Chapter
  • First Online:
Mathesis Universalis, Computability and Proof

Part of the book series: Synthese Library ((SYLI,volume 412))

  • 216 Accesses

Abstract

Mathematical logic provides a formal language to describe complex abstract phenomena whereby a finite formula written in a finite alphabet states a property of an object that may even be infinite. Thus, the complexity of the underlying objects is abstracted away to give way for a simple syntactic description, a kind of mathesis universalis. The complexity, however, continues affecting which ways of reasoning are valid.

Structural proof theory reasons using proof objects more complex than individual formulas. One of its goals is to find minimal additional structures, depending on the complexity of the underlying objects, sufficient for efficient and modular reasoning about them.

In this paper, we are primarily interested in both the global structure used for reasoning and the local part of this structure employed to justify single inference steps. We provide recently developed examples where adapting the global structure of the sequent to the local structure of (potentially infinite) Kripke models yielded both quantitative and qualitative benefits in establishing fundamental logical properties such as complexity and interpolation.

The author is funded by FWF projects S 11405 (RiSE) and Y 544-N23.

This is a preview of subscription content, log in via an institution to check access.

Access this chapter

Chapter
USD 29.95
Price excludes VAT (USA)
  • Available as PDF
  • Read on any device
  • Instant download
  • Own it forever
eBook
USD 99.00
Price excludes VAT (USA)
  • Available as EPUB and PDF
  • Read on any device
  • Instant download
  • Own it forever
Softcover Book
USD 129.99
Price excludes VAT (USA)
  • Compact, lightweight edition
  • Dispatched in 3 to 5 business days
  • Free shipping worldwide - see info
Hardcover Book
USD 129.99
Price excludes VAT (USA)
  • Durable hardcover edition
  • Dispatched in 3 to 5 business days
  • Free shipping worldwide - see info

Tax calculation will be finalised at checkout

Purchases are for personal use only

Institutional subscriptions

Notes

  1. 1.

    Needless to say, this is not a cultist dogma claiming all logics to have analytic descriptions. Exceptions are made for degenerate logics, for monstrosities artificially created to defy proof-theoretic analysis, and for logics involving objectively complex notions, e.g., fixpoints (though the latter are still pursued and not entirely without success, cf., e.g., a recent survey of proof systems for common knowledge by Marti and Studer 2018). But an idea that adding one axiom may rob a logic of its cut-free representation is often met with disbelief and resistance.

  2. 2.

    Which is almost inevitably interpreted to be cut-free.

  3. 3.

    Bibliographic note: These two articles constituted Gentzen’s dissertation and were originally published in separate Hefte (issues) of Mathematische Zeitschrift in German. Their translation into English, combined into one article as originally intended, can be found in Gentzen (1969).

  4. 4.

    Exceptions such as Gentzen’s sequents for intuitionistic logic only prove the rule.

  5. 5.

    A preorder is a reflexive and transitive binary relation.

  6. 6.

    According to a private communication with Melvin Fitting, at the time he did not know of Maehara’s results, which were published in German. In fact, I had the pleasure of translating them for him to confirm the connection as recently as in 2015. Given that Beth did not reference Maehara either, it is likely that the two systems have been developed independently, which often happens with fruitful ideas in proof theory.

  7. 7.

    Some intuitionistic semantics insist on the proof of a disjunction having to carry information about which disjunct was proved, but the official BHK interpretation does not (see Moschovakis 2015).

  8. 8.

    An intermediate logic is a logic between Int and classical propositional logic.

  9. 9.

    Alternatively, Fitting suggested working in a language without implication, where formulas never reach the other side of the sequent arrow ⇒. He called such sequent systems symmetric (Fitting 1983). However, the symmetric option is only available for classical-based logics since implication is not definable through other connectives intuitionistically.

  10. 10.

    The symbol \(\mho \) is used as a unit in physics. Due to its reciprocal connection to ohm, denoted Ω, the symbol \(\mho \) represents an upside down Ω and its pronunciation, mho is the word ohm read backwards.

  11. 11.

    The polarity of p occurring in \(\overline {E}\mathstrut ^{(k)}\) (in E (k)) is opposite to (the same as) the polarity of p in E. The operations and preserve polarity.

  12. 12.

    We apply the term principle to components of a hypersequent by analogy with its usage for formulas: a principle component is the one in the succedent of the rule, to which the rule is applied, i.e., the one without which this rule would not have been applicable.

  13. 13.

    Bibliographic note: Both papers Minc (1971) and Mints (1997) belong to the same person, whose preferred spelling was Mints. The spelling Minc originated from an alternative transliteration system from the Cyrillic alphabet. The original Cyrillic spelling Минц can be found, e.g., in Минц (1968).

References

Download references

Acknowledgements

I would like to thank Stefania Centrone, Sara Negri, Denis Sarikaya, and Peter Schuster for organizing the Kolleg, which brought together so many outstanding scientists from different communities and different generations that I remember often feeling an awe and inspiration in equal measure during talks and after-talk discussions. I thank Agata Ciabattoni for her continuous support. I am grateful for the anonymous reviewer for their words of encouragement. I am also deeply indebted to Melvin Fitting, who was kind enough to take a look at this paper and immediately saw how to improve it. I should also say this paper would not have happened without everything I had learned from him over the years.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Roman Kuznets .

Editor information

Editors and Affiliations

Rights and permissions

Reprints and permissions

Copyright information

© 2019 Springer Nature Switzerland AG

About this chapter

Check for updates. Verify currency and authenticity via CrossMark

Cite this chapter

Kuznets, R. (2019). Through an Inference Rule, Darkly. In: Centrone, S., Negri, S., Sarikaya, D., Schuster, P.M. (eds) Mathesis Universalis, Computability and Proof. Synthese Library, vol 412. Springer, Cham. https://doi.org/10.1007/978-3-030-20447-1_10

Download citation

Publish with us

Policies and ethics