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SLE 2020
Sun 15 - Fri 20 November 2020 Online Conference
co-located with SPLASH 2020
Mon 16 Nov 2020 15:00 - 15:20 at SPLASH-III - Chair(s): Paddy Krishnan
Tue 17 Nov 2020 03:00 - 03:20 at SPLASH-III - Chair(s): Ralf Laemmel

Parsing Expression Grammars (PEGs) are a recognition-based formalism which allows to describe the syntactical and the lexical elements of a language. The main difference between Context-Free Grammars (CFGs) and PEGs relies on the interpretation of the choice operator: while the CFGs' unordered choice $e \mid e'$ is interpreted as the union of the languages recognized by $e$ and $e'$, the PEGs' prioritized choice $e / e'$ discards $e'$ if $e$ succeeds. Such subtle, but important difference, changes the language
recognized and yields more efficient parsing algorithms. This paper proposes a rewriting logic semantics for PEGs. We start
with a rewrite theory giving meaning to the usual constructs in PEGs. Later, we show that cuts, a mechanism for controlling backtracks in PEGs, finds also a natural representation in our framework.
We generalize such mechanism, allowing for both local and global cuts with a precise, unified and formal semantics. Hence, our work strives at better understanding and controlling backtracks in parsers for PEGs. The semantics we propose is executable and, besides being a parser with modest efficiency, it can be used as a playground to test different optimization ideas. More importantly, it is a mathematical tool that can be used for different analyses.

Mon 16 Nov

Displayed time zone: Central Time (US & Canada) change

15:00 - 15:40
SLE at SPLASH-III +12h
Chair(s): Paddy Krishnan Oracle Labs, Australia
15:00
20m
Talk
A Semantic Framework for PEGs
SLE
Sergio Queiroz de Medeiros Universidade Federal do Rio Grande do Norte, Carlos Olarte Federal University of Rio Grande do Norte, Brazil
Link to publication DOI Pre-print Media Attached
15:20
20m
Talk
Untangling Mechanized Proofs
SLE
DOI Pre-print Media Attached

Tue 17 Nov

Displayed time zone: Central Time (US & Canada) change

03:00 - 03:40
SLE at SPLASH-III
Chair(s): Ralf Laemmel Facebook London
03:00
20m
Talk
A Semantic Framework for PEGs
SLE
Sergio Queiroz de Medeiros Universidade Federal do Rio Grande do Norte, Carlos Olarte Federal University of Rio Grande do Norte, Brazil
Link to publication DOI Pre-print Media Attached
03:20
20m
Talk
Untangling Mechanized Proofs
SLE
DOI Pre-print Media Attached