Summary: Slide 1
Untyped Algorithmic Equality
for Martin­L˜of's Logical Framework
with Surjective Pairs
Andreas Abel
joint work with Thierry Coquand
TLCA'05
Nara, Japan
April 21, 2005
Work supported by: TYPES & APPSEM­II (EU), CoVer (SSF)
Slide 2
Background: ##­equality
. Checking dependent types requires equality test
. One approach: reduce to normal form and compare
syntactically
. Works fine for #­equality
. Problem with #­reduction: surjective pairing destroys
confluence (Klop 1980)
. Even subject reduction fails:
z : Pair A (#x. F x) # (z L, z R) : Pair A (# . F (z L))

Source: Abel, Andreas - Theoretische Informatik, Ludwig-Maximilians-Universität München

Collections: Computer Technologies and Information Sciences