20 research outputs found
Maximum flow is approximable by deterministic constant-time algorithm in sparse networks
We show a deterministic constant-time parallel algorithm for finding an
almost maximum flow in multisource-multitarget networks with bounded degrees
and bounded edge capacities. As a consequence, we show that the value of the
maximum flow over the number of nodes is a testable parameter on these
networks.Comment: 8 page
Random local algorithms
Consider the problem when we want to construct some structure on a bounded
degree graph, e.g. an almost maximum matching, and we want to decide about each
edge depending only on its constant radius neighbourhood. We show that the
information about the local statistics of the graph does not help here. Namely,
if there exists a random local algorithm which can use any local statistics
about the graph, and produces an almost optimal structure, then the same can be
achieved by a random local algorithm using no statistics.Comment: 9 page
Π‘ΡΠ±Π»ΡΠ½ΡΠΉΠ½ΠΈΠΉ ΠΎΠΏΡΠΈΠΌΠ°Π»ΡΠ½ΠΈΠΉ Π½Π°Π±Π»ΠΈΠΆΠ΅Π½ΠΈΠΉ Π°Π»Π³ΠΎΡΠΈΡΠΌ ΡΠ΅ΠΎΠΏΡΠΈΠΌΡΠ·Π°ΡΡΡ Π΄Π»Ρ Π·Π°Π΄Π°ΡΡ ΠΏΡΠΎ ΠΌΡΠ½ΡΠΌΠ°Π»ΡΠ½Π΅ Π²Π΅ΡΡΠΈΠ½Π½Π΅ ΠΏΠΎΠΊΡΠΈΡΡΡ Π³ΡΠ°ΡΠ°
ΠΠ° Π½Π°Π±Π»ΠΈΠΆΠ΅Π½ΠΎΠ³ΠΎ ΡΠΎΠ·Π²βΡΠ·Π°Π½Π½Ρ Π΄ΠΈΡΠΊΡΠ΅ΡΠ½ΠΈΡ
Π·Π°Π΄Π°Ρ ΠΎΠΏΡΠΈΠΌΡΠ·Π°ΡΡΡ Π²ΠΈΠ½ΠΈΠΊΠ°Ρ ΡΠ°ΠΊΠ° iΠ΄Π΅Ρ: ΡΠΈ ΠΌΠΎΠΆΠ½Π°, Π²ΠΈΡ
ΠΎΠ΄ΡΡΠΈ Π· ΡΠ½ΡΠΎΡΠΌΠ°ΡΡΡ ΠΏΡΠΎ ΠΎΠΏΡΠΈΠΌΠ°Π»ΡΠ½ΠΈΠΉ ΡΠΎΠ·Π²βΡΠ·ΠΎΠΊ Π΅ΠΊΠ·Π΅ΠΌΠΏΠ»ΡΡΠ° Π·Π°Π΄Π°ΡΡ (Π°Π±ΠΎ Π±Π»ΠΈΠ·ΡΠΊΠΎΠ³ΠΎ Π΄ΠΎ Π½ΡΠΎΠ³ΠΎ), Π²ΠΈΠΊΠΎΡΠΈΡΡΠΎΠ²ΡΠ²Π°ΡΠΈ ΡΡ ΡΠ½ΡΠΎΡΠΌΠ°ΡΡΡ Π΄Π»Ρ Π·Π½Π°Ρ
ΠΎΠ΄ΠΆΠ΅Π½Π½Ρ ΠΎΠΏΡΠΈΠΌΠ°Π»ΡΠ½ΠΎΠ³ΠΎ (Π°Π±ΠΎ Π±Π»ΠΈΠ·ΡΠΊΠΎΠ³ΠΎ Π΄ΠΎ Π½ΡΠΎΠ³ΠΎ) ΡΠΎΠ·Π²βΡΠ·ΠΊΡ Π΅ΠΊΠ·Π΅ΠΌΠΏΠ»ΡΡΠ° Π·Π°Π΄Π°ΡΡ, ΠΎΡΡΠΈΠΌΠ°Π½ΠΎΠ³ΠΎ Π² ΡΠ΅Π·ΡΠ»ΡΡΠ°Ρi Π½Π΅Π·Π½Π°ΡΠ½ΠΈΡ
Π»ΠΎΠΊΠ°Π»ΡΠ½ΠΈΡ
ΠΌΠΎΠ΄ΠΈΡiΠΊΠ°ΡiΠΉ Π²ΠΈΡ
iΠ΄Π½ΠΎΠ³ΠΎ Π΅ΠΊΠ·Π΅ΠΌΠΏΠ»ΡΡΠ°. Π¦Π΅ΠΉ ΠΏiΠ΄Ρ
iΠ΄, Π½Π°Π·Π²Π°Π½ΠΈΠΉ ΡΠ΅ΠΎΠΏΡΠΈΠΌΡΠ·Π°ΡΡΡΡ, Π΄ΠΎΠ·Π²ΠΎΠ»ΡΡ Π² Π΄Π΅ΡΠΊΠΈΡ
Π²ΠΈΠΏΠ°Π΄ΠΊΠ°Ρ
ΠΎΡΡΠΈΠΌΠ°ΡΠΈ ΠΊΡΠ°ΡΡ ΡΠΊiΡΡΡ Π½Π°Π±Π»ΠΈΠΆΠ΅Π½Π½Ρ (ΡΠΊΠ΅ Π²ΠΈΠ·Π½Π°ΡΠ°ΡΡΡΡΡ ΡΠΊ Π²iΠ΄Π½ΠΎΡΠ΅Π½Π½Ρ Π·Π½Π°ΡΠ΅Π½Π½Ρ Π½Π°Π±Π»ΠΈΠΆΠ΅Π½ΠΎΠ³ΠΎ ΡΠΎΠ·Π²βΡΠ·ΠΊΡ Π΄ΠΎ ΡΠΎΡΠ½ΠΎΠ³ΠΎ i Π½Π°Π·ΠΈΠ²Π°ΡΡΡΡΡ Π²iΠ΄Π½ΠΎΡΠ΅Π½Π½ΡΠΌ Π°ΠΏΡΠΎΠΊΡΠΈΠΌΠ°ΡiΡ) Ρ Π»ΠΎΠΊΠ°Π»ΡΠ½ΠΎ ΠΌΠΎΠ΄ΠΈΡiΠΊΠΎΠ²Π°Π½ΠΈΡ
Π΅ΠΊΠ·Π΅ΠΌΠΏΠ»ΡΡΠ°Ρ
, Π½iΠΆ Ρ Π²ΠΈΡ
iΠ΄Π½ΠΈΡ
. Π―ΠΊΡΠΎ Π΄Π»Ρ Π΄Π΅ΡΠΊΠΈΡ
ΠΎΠΏΡΠΈΠΌiΠ·Π°ΡiΠΉΠ½ΠΈΡ
Π·Π°Π΄Π°Ρ Π²iΠ΄Π½ΠΎΡΠ΅Π½Π½Ρ Π°ΠΏΡΠΎΠΊΡΠΈΠΌΠ°ΡiΡ Π½Π΅ ΠΌΠΎΠΆΠ½Π° ΠΏΠΎΠΊΡΠ°ΡΠΈΡΠΈ (Π½Π°ΠΏΡΠΈΠΊΠ»Π°Π΄, Ρ ΠΊΠ»Π°Ρi Π²ΡiΡ
Π½Π°Π±Π»ΠΈΠΆΠ΅Π½ΠΈΡ
Π°Π»Π³ΠΎΡΠΈΡΠΌiΠ² ΡΠ· ΠΏΠΎΠ»iΠ½ΠΎΠΌiΠ°Π»ΡΠ½ΠΎΡ ΡΠΊΠ»Π°Π΄Π½iΡΡΡ), ΡΠΎ ΡΠ°ΠΊΠ΅ Π²iΠ΄Π½ΠΎΡΠ΅Π½Π½Ρ Π½Π°Π·ΠΈΠ²Π°ΡΡΡ ΠΏΠΎΡΠΎΠ³ΠΎΠ²ΠΈΠΌ Π°Π±ΠΎ ΠΎΠΏΡΠΈΠΌΠ°Π»ΡΠ½ΠΈΠΌ (Π°Π»Π³ΠΎΡΠΈΡΠΌ Π½Π° ΡΠΊΠΎΠΌΡ Π΄ΠΎΡΡΠ³Π°ΡΡΡΡΡ ΡΠ΅ Π²iΠ΄Π½ΠΎΡΠ΅Π½Π½Ρ ΡΠ°ΠΊΠΎΠΆ Π½Π°Π·ΠΈΠ²Π°ΡΡΡ ΠΏΠΎΡΠΎΠ³ΠΎΠ²ΠΈΠΌ Π°Π±ΠΎ ΠΎΠΏΡΠΈΠΌΠ°Π»ΡΠ½ΠΈΠΌ). Π‘ΠΊΠ»Π°Π΄Π½ΡΡΡΡ Π°Π»Π³ΠΎΡΠΈΡΠΌΡΠ² ΠΎΡΡΠ½ΡΡΡΡΡΡ ΠΊΡΠ»ΡΠΊΡΡΡΡ Π·Π²Π΅ΡΠ½Π΅Π½Ρ (Π·Π°ΠΏΠΈΡΡΠ²) Π΄ΠΎ ΡΠΏΠ΅ΡΡΠ°Π»ΡΠ½ΠΎΠ³ΠΎ ΠΎΡΠ°ΠΊΡΠ»Ρ. ΠΠ»Ρ ΡΠ΅ΠΎΠΏΡΠΈΠΌΡΠ·Π°ΡΡΡ Π·Π°Π΄Π°ΡΡ ΠΏΡΠΎ ΠΌΡΠ½ΡΠΌΠ°Π»ΡΠ½Π΅ Π²Π΅ΡΡΠΈΠ½Π½Π΅ ΠΏΠΎΠΊΡΠΈΡΡΡ Π³ΡΠ°ΡΠ° (Π·Π° Π΄ΠΎΠ±Π°Π²Π»Π΅Π½Π½Ρ ΠΎΠ΄Π½ΡΡΡ Π²Π΅ΡΡΠΈΠ½ΠΈ Ρ Π΄Π΅ΡΠΊΠΎΡ ΠΌΠ½ΠΎΠΆΠΈΠ½ΠΈ ΡΠ΅Π±Π΅Ρ) ΠΎΡΡΠΈΠΌΠ°Π½ΠΈΠΉ (3/2)-Π½Π°Π±Π»ΠΈΠΆΠ΅Π½ΠΈΠΉ Π°Π»Π³ΠΎΡΠΈΡΠΌ ΡΠ· Π°Π΄ΠΈΡΠΈΠ²Π½ΠΎΡ ΠΏΠΎΠΌΠΈΠ»ΠΊΠΎΡ Π· ΡΡΠ±Π»ΡΠ½ΡΠΉΠ½ΠΎΡ (ΠΊΠΎΠ½ΡΡΠ°Π½ΡΠ½ΠΎΡ) ΡΠΊΠ»Π°Π΄Π½ΡΡΡΡ. ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΠΎ Π²ΡΠ΄Π½ΠΎΡΠ΅Π½Π½Ρ Π°ΠΏΡΠΎΠΊΡΠΈΠΌΠ°ΡΡΡ 3/2 Ρ ΠΏΠΎΡΠΎΠ³ΠΎΠ²ΠΈΠΌ Ρ ΠΊΠ»Π°ΡΡ Π°Π»Π³ΠΎΡΠΈΡΠΌΡΠ² ΡΠ· ΠΊΠΎΠ½ΡΡΠ°Π½ΡΠ½ΠΎΡ ΡΠΊΠ»Π°Π΄Π½ΡΡΡΡ.ΠΡΠΈ ΠΏΡΠΈΠ±Π»ΠΈΠΆΠ΅Π½Π½ΠΎΠΌ ΡΠ΅ΡΠ΅Π½ΠΈΠΈ Π΄ΠΈΡΠΊΡΠ΅ΡΠ½ΡΡ
Π·Π°Π΄Π°Ρ ΠΎΠΏΡΠΈΠΌΠΈΠ·Π°ΡΠΈΠΈ Π²ΠΎΠ·Π½ΠΈΠΊΠ°Π΅Ρ ΡΠ°ΠΊΠ°Ρ ΠΈΠ΄Π΅Ρ: ΠΌΠΎΠΆΠ½ΠΎ Π»ΠΈ, ΠΈΡΡ
ΠΎΠ΄Ρ ΠΈΠ· ΠΈΠ½ΡΠΎΡΠΌΠ°ΡΠΈΠΈ ΠΎΠ± ΠΎΠΏΡΠΈΠΌΠ°Π»ΡΠ½ΠΎΠΌ ΡΠ΅ΡΠ΅Π½ΠΈΠΈ ΡΠΊΠ·Π΅ΠΌΠΏΠ»ΡΡΠ° Π·Π°Π΄Π°ΡΠΈ (ΠΈΠ»ΠΈ Π±Π»ΠΈΠ·ΠΊΠΎΠ³ΠΎ ΠΊ Π½Π΅ΠΌΡ), ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°ΡΡ ΡΡΡ ΠΈΠ½ΡΠΎΡΠΌΠ°ΡΠΈΡ Π΄Π»Ρ Π½Π°Ρ
ΠΎΠΆΠ΄Π΅Π½ΠΈΡ ΠΎΠΏΡΠΈΠΌΠ°Π»ΡΠ½ΠΎΠ³ΠΎ (ΠΈΠ»ΠΈ Π±Π»ΠΈΠ·ΠΊΠΎΠ³ΠΎ ΠΊ Π½Π΅ΠΌΡ) ΡΠ΅ΡΠ΅Π½ΠΈΡ ΡΠΊΠ·Π΅ΠΌΠΏΠ»ΡΡΠ° Π·Π°Π΄Π°ΡΠΈ, ΠΏΠΎΠ»ΡΡΠ΅Π½Π½ΠΎΠ³ΠΎ Π² ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΠ΅ Π½Π΅Π·Π½Π°ΡΠΈΡΠ΅Π»ΡΠ½ΡΡ
Π»ΠΎΠΊΠ°Π»ΡΠ½ΡΡ
ΠΌΠΎΠ΄ΠΈΡΠΈΠΊΠ°ΡΠΈΠΉ ΠΈΡΡ
ΠΎΠ΄Π½ΠΎΠ³ΠΎ ΡΠΊΠ·Π΅ΠΌΠΏΠ»ΡΡΠ°. ΠΠ°Π½Π½ΡΠΉ ΠΏΠΎΠ΄Ρ
ΠΎΠ΄, Π½Π°Π·Π²Π°Π½Π½ΡΠΉ ΡΠ΅ΠΎΠΏΡΠΈΠΌΠΈΠ·Π°ΡΠΈΠ΅ΠΉ, ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ, Π½Π°ΠΏΡΠΈΠΌΠ΅Ρ, Π² Π½Π΅ΠΊΠΎΡΠΎΡΡΡ
ΡΠ»ΡΡΠ°ΡΡ
ΠΏΠΎΠ»ΡΡΠΈΡΡ Π»ΡΡΡΠ΅Π΅ ΠΊΠ°ΡΠ΅ΡΡΠ²ΠΎ ΠΏΡΠΈΠ±Π»ΠΈΠΆΠ΅Π½ΠΈΡ (ΠΊΠΎΡΠΎΡΠΎΠ΅ ΠΎΠΏΡΠ΅Π΄Π΅Π»ΡΠ΅ΡΡΡ ΠΊΠ°ΠΊ ΠΎΡΠ½ΠΎΡΠ΅Π½ΠΈΠ΅ Π·Π½Π°ΡΠ΅Π½ΠΈΡ ΠΏΡΠΈΠ±Π»ΠΈΠΆΠ΅Π½Π½ΠΎΠ³ΠΎ ΡΠ΅ΡΠ΅Π½ΠΈΡ ΠΊ ΡΠΎΡΠ½ΠΎΠΌΡ ΠΈ Π½Π°Π·ΡΠ²Π°Π΅ΡΡΡ ΠΎΡΠ½ΠΎΡΠ΅Π½ΠΈΠ΅ΠΌ Π°ΠΏΠΏΡΠΎΠΊΡΠΈΠΌΠ°ΡΠΈΠΈ) Π² Π»ΠΎΠΊΠ°Π»ΡΠ½ΠΎ ΠΌΠΎΠ΄ΠΈΡΠΈΡΠΈΡΠΎΠ²Π°Π½Π½ΡΡ
ΡΠΊΠ·Π΅ΠΌΠΏΠ»ΡΡΠ°Ρ
, ΡΠ΅ΠΌ Π² ΠΈΡΡ
ΠΎΠ΄Π½ΡΡ
. ΠΡΠ»ΠΈ Π΄Π»Ρ Π½Π΅ΠΊΠΎΡΠΎΡΡΡ
ΠΎΠΏΡΠΈΠΌΠΈΠ·Π°ΡΠΈΠΎΠ½Π½ΡΡ
Π·Π°Π΄Π°Ρ ΠΎΡΠ½ΠΎΡΠ΅Π½ΠΈΠ΅ Π°ΠΏΠΏΡΠΎΠΊΡΠΈΠΌΠ°ΡΠΈΠΈ Π½Π΅Π»ΡΠ·Ρ ΡΠ»ΡΡΡΠΈΡΡ (Π½Π°ΠΏΡΠΈΠΌΠ΅Ρ, Π² ΠΊΠ»Π°ΡΡΠ΅ Π²ΡΠ΅Ρ
ΠΏΡΠΈΠ±Π»ΠΈΠΆΠ΅Π½Π½ΡΡ
Π°Π»Π³ΠΎΡΠΈΡΠΌΠΎΠ² Ρ ΠΏΠΎΠ»ΠΈΠ½ΠΎΠΌΠΈΠ°Π»ΡΠ½ΠΎΠΉ ΡΠ»ΠΎΠΆΠ½ΠΎΡΡΡΡ), ΡΠΎ ΡΠ°ΠΊΠΎΠ΅ ΠΎΡΠ½ΠΎΡΠ΅Π½ΠΈΠ΅ Π½Π°Π·ΡΠ²Π°ΡΡ ΠΏΠΎΡΠΎΠ³ΠΎΠ²ΡΠΌ ΠΈΠ»ΠΈ ΠΎΠΏΡΠΈΠΌΠ°Π»ΡΠ½ΡΠΌ (Π°Π»Π³ΠΎΡΠΈΡΠΌ Π½Π° ΠΊΠΎΡΠΎΡΠΎΠΌ Π΄ΠΎΡΡΠΈΠ³Π°Π΅ΡΡΡ ΡΡΠΎ ΠΎΡΠ½ΠΎΡΠ΅Π½ΠΈΠ΅ ΡΠ°ΠΊΠΆΠ΅ Π½Π°Π·ΡΠ²Π°ΡΡ ΠΏΠΎΡΠΎΠ³ΠΎΠ²ΡΠΌ ΠΈΠ»ΠΈ ΠΎΠΏΡΠΈΠΌΠ°Π»ΡΠ½ΡΠΌ). Π‘Π»ΠΎΠΆΠ½ΠΎΡΡΡ Π°Π»Π³ΠΎΡΠΈΡΠΌΠΎΠ² ΠΎΡΠ΅Π½ΠΈΠ²Π°Π΅ΡΡΡ ΠΊΠΎΠ»ΠΈΡΠ΅ΡΡΠ²ΠΎΠΌ ΠΎΠ±ΡΠ°ΡΠ΅Π½ΠΈΠΉ (Π·Π°ΠΏΡΠΎΡΠΎΠ²) ΠΊ ΡΠΏΠ΅ΡΠΈΠ°Π»ΡΠ½ΠΎΠΌΡ ΠΎΡΠ°ΠΊΡΠ»Ρ. ΠΠ»Ρ ΡΠ΅ΠΎΠΏΡΠΈΠΌΠΈΠ·Π°ΡΠΈΠΈ Π·Π°Π΄Π°ΡΠΈ ΠΎ ΠΌΠΈΠ½ΠΈΠΌΠ°Π»ΡΠ½ΠΎΠΌ Π²Π΅ΡΡΠΈΠ½Π½ΠΎΠΌ ΠΏΠΎΠΊΡΡΡΠΈΠΈ Π³ΡΠ°ΡΠ° (ΠΏΡΠΈ Π΄ΠΎΠ±Π°Π²Π»Π΅Π½ΠΈΠΈ ΠΎΠ΄Π½ΠΎΠΉ Π²Π΅ΡΡΠΈΠ½Ρ ΠΈ Π½Π΅ΠΊΠΎΡΠΎΡΠΎΠ³ΠΎ ΠΌΠ½ΠΎΠΆΠ΅ΡΡΠ²Π° ΡΠ΅Π±Π΅Ρ) ΠΏΠΎΠ»ΡΡΠ΅Π½ (3/2)-ΠΏΡΠΈΠ±Π»ΠΈΠΆΠ΅Π½Π½ΡΠΉ Π°Π»Π³ΠΎΡΠΈΡΠΌ Ρ Π°Π΄Π΄ΠΈΡΠΈΠ²Π½ΠΎΠΉ ΠΎΡΠΈΠ±ΠΊΠΎΠΉ Ρ ΡΡΠ±Π»ΠΈΠ½Π΅ΠΉΠ½ΠΎΠΉ (ΠΊΠΎΠ½ΡΡΠ°Π½ΡΠ½ΠΎΠΉ) ΡΠ»ΠΎΠΆΠ½ΠΎΡΡΡΡ. ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ ΠΎΡΠ½ΠΎΡΠ΅Π½ΠΈΠ΅ Π°ΠΏΠΏΡΠΎΠΊΡΠΈΠΌΠ°ΡΠΈΠΈ 3/2 ΡΠ²Π»ΡΠ΅ΡΡΡ ΠΏΠΎΡΠΎΠ³ΠΎΠ²ΡΠΌ Π² ΠΊΠ»Π°ΡΡΠ΅ Π°Π»Π³ΠΎΡΠΈΡΠΌΠΎΠ² Ρ ΠΊΠΎΠ½ΡΡΠ°Π½ΡΠ½ΠΎΠΉ ΡΠ»ΠΎΠΆΠ½ΠΎΡΡΡΡ.With the approximate solution of discrete optimization problems such idea arises: is it possible, taking into account the information about the optimal solution of an instance (or close to it), use this information to find the optimal (or close to it) solution of instance problem obtained as a result of minor local modifications of the initial instance. This approach, called reoptimization, allows, for example, in some cases, getting the best quality of approximation (which is defined as the ratio between the value of an approximate solution to the exact ratio and called approximation ratio) in locally modified instances than at initials. If for some tasks approximation ratio can not be improved (e.g. in class of all approximation algorithms with polynomial complexity), the ratio is called the threshold or optimal (algorithm which achieved this ratio is also called the threshold or optimal). The complexity of the algorithms is estimated by the number of hits (queries) to a special oracle. For reoptimization of minimum vertex cover problem (with addition of one vertex and some set of edges) (3/2)-approximation algorithm with additive error and sublinear (constant) complexity is received. It is shown that the approximation ratio of 3/2 is the threshold in the class of algorithms with constant complexity
Lower Bounds on Query Complexity for Testing Bounded-Degree CSPs
In this paper, we consider lower bounds on the query complexity for testing
CSPs in the bounded-degree model.
First, for any ``symmetric'' predicate except \equ
where , we show that every (randomized) algorithm that distinguishes
satisfiable instances of CSP(P) from instances -far
from satisfiability requires queries where is the
number of variables and is a constant that depends on and
. This breaks a natural lower bound , which is
obtained by the birthday paradox. We also show that every one-sided error
tester requires queries for such . These results are hereditary
in the sense that the same results hold for any predicate such that
. For EQU, we give a one-sided error tester
whose query complexity is . Also, for 2-XOR (or,
equivalently E2LIN2), we show an lower bound for
distinguishing instances between -close to and -far
from satisfiability.
Next, for the general k-CSP over the binary domain, we show that every
algorithm that distinguishes satisfiable instances from instances
-far from satisfiability requires queries. The
matching NP-hardness is not known, even assuming the Unique Games Conjecture or
the -to- Conjecture. As a corollary, for Maximum Independent Set on
graphs with vertices and a degree bound , we show that every
approximation algorithm within a factor d/\poly\log d and an additive error
of requires queries. Previously, only super-constant
lower bounds were known
Optimal Constant-Time Approximation Algorithms and (Unconditional) Inapproximability Results for Every Bounded-Degree CSP
Raghavendra (STOC 2008) gave an elegant and surprising result: if Khot's
Unique Games Conjecture (STOC 2002) is true, then for every constraint
satisfaction problem (CSP), the best approximation ratio is attained by a
certain simple semidefinite programming and a rounding scheme for it. In this
paper, we show that similar results hold for constant-time approximation
algorithms in the bounded-degree model. Specifically, we present the
followings: (i) For every CSP, we construct an oracle that serves an access, in
constant time, to a nearly optimal solution to a basic LP relaxation of the
CSP. (ii) Using the oracle, we give a constant-time rounding scheme that
achieves an approximation ratio coincident with the integrality gap of the
basic LP. (iii) Finally, we give a generic conversion from integrality gaps of
basic LPs to hardness results. All of those results are \textit{unconditional}.
Therefore, for every bounded-degree CSP, we give the best constant-time
approximation algorithm among all. A CSP instance is called -far from
satisfiability if we must remove at least an -fraction of constraints
to make it satisfiable. A CSP is called testable if there is a constant-time
algorithm that distinguishes satisfiable instances from -far
instances with probability at least . Using the results above, we also
derive, under a technical assumption, an equivalent condition under which a CSP
is testable in the bounded-degree model
Hereditary properties of permutations are strongly testable
We show that for every hereditary permutation property and every β0 > 0, there exists an integer M such that if a permutation Ο is βo-far from in the Kendall's tau distance, then a random subpermutation of Ο of order M has the property P with probability at most β0. This settles an open problem whether hereditary permutation properties are strongly testable, i.e., testable with respect to the Kendall's tau distance, which is considered to be the edit distance for permutations. Our method also yields a proof of a conjecture of Hoppen, Kohayakawa, Moreira and Sampaio on the relation of the rectangular distance and the Kendall's tau distance of a permutation from a hereditary property