The structure of differential invariants and differential cut elimination
The biggest challenge in hybrid systems verification is the handling of differential equations. Because computable closed-form solutions only exist for very simple differential equations, proof certificates have been proposed for more scalable verification. Search procedures for these proof certificates are still rather ad-hoc, though, because the problem structure is only understood poorly. We investigate differential invariants, which define an induction principle for differential equations and which can be checked for invariance along a differential equation just by using their differential structure, without having to solve them. We study the structural properties of differential invariants. To analyze trade-offs for proof search complexity, we identify more than a dozen relations between several classes of differential invariants and compare their deductive power. As our main results, we analyze the deductive power of differential cuts and the deductive power of differential invariants with auxiliary differential variables. We refute the differential cut elimination hypothesis and show that, unlike standard cuts, differential cuts are fundamental proof principles that strictly increase the deductive power. We also prove that the deductive power increases further when adding auxiliary differential variables to the dynamics.
@ARTICLE{DBLP:journals/lmcs/Platzer12,
pdf = {https://lmcs.episciences.org/809/pdf},
author = {Andr{\'e} Platzer},
title = {The Structure of Differential Invariants
and Differential Cut Elimination},
journal = {Logical Methods in Computer Science},
volume = {8},
number = {4},
year = {2012},
pages = {1-38},
doi = {10.2168/LMCS-8(4:16)2012},
keywords = {Proof theory, differential equations,
differential invariants, differential cut
elimination, differential dynamic logic
hybrid systems, logics of programs,
real differential semialgebraic geometry},
abstract = {
The biggest challenge in hybrid systems verification is
the handling of differential equations. Because
computable closed-form solutions only exist for very
simple differential equations, proof certificates have
been proposed for more scalable verification. Search
procedures for these proof certificates are still rather
ad-hoc, though, because the problem structure is only
understood poorly. We investigate differential
invariants, which define an induction principle for
differential equations and which can be checked for
invariance along a differential equation just by using
their differential structure, without having to solve
them. We study the structural properties of differential
invariants. To analyze trade-offs for proof search
complexity, we identify more than a dozen relations
between several classes of differential invariants and
compare their deductive power. As our main results, we
analyze the deductive power of differential cuts and the
deductive power of differential invariants with
auxiliary differential variables. We refute the
differential cut elimination hypothesis and show that,
unlike standard cuts, differential cuts are fundamental
proof principles that strictly increase the deductive
power. We also prove that the deductive power increases
further when adding auxiliary differential variables to
the dynamics.
}
}```