Infinite Games Recap and Outlook Martin Zimmermann Saarland - - PowerPoint PPT Presentation

infinite games
SMART_READER_LITE
LIVE PREVIEW

Infinite Games Recap and Outlook Martin Zimmermann Saarland - - PowerPoint PPT Presentation

Infinite Games Recap and Outlook Martin Zimmermann Saarland University July 26th, 2016 Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 1/35 Plan for Today Review Change Log Lecture Notes Exam Organizational


slide-1
SLIDE 1

Infinite Games

Recap and Outlook

Martin Zimmermann

Saarland University

July 26th, 2016

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 1/35

slide-2
SLIDE 2

Plan for Today

Review Change Log Lecture Notes Exam Organizational Matters Questions Outlook: Even More Games

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 2/35

slide-3
SLIDE 3

Review

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 3/35

slide-4
SLIDE 4

Reachability

Name: Reachability Game Format: (A, Reach(R)) with R ⊆ V

v4 v1 v3 v5 v7 v0 v2 v6 v8

Winning condition: Occ(ρ) ∩ R = ∅ Solution complexity: linear time in |E| Algorithm: attractor Memory requirements for Player 0: uniform positional Memory requirements for Player 1: uniform positional Dual game: safety

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 4/35

slide-5
SLIDE 5

Safety

Name: Safety Game Format: (A, Safety(S)) with S ⊆ V

v4 v1 v3 v5 v7 v0 v2 v6 v8

Winning condition: Occ(ρ) ⊆ S Solution complexity: linear time in |E| Algorithm: dualize + attractor Memory requirements for Player 0: uniform positional Memory requirements for Player 1: uniform positional Dual game: reachability

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 5/35

slide-6
SLIDE 6

B¨ uchi

Name: B¨ uchi Game Format: (A, B¨ uchi(F)) with F ⊆ V

v4 v1 v3 v5 v7 v0 v2 v6 v8

Winning condition: Inf(ρ) ∩ F = ∅ Solution complexity: P Algorithm: iterated attractor Memory requirements for Player 0: uniform positional Memory requirements for Player 1: uniform positional Dual game: co-B¨ uchi

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 6/35

slide-7
SLIDE 7

Co-B¨ uchi

Name: Co-B¨ uchi Game Format: (A, coB¨ uchi(C)) with C ⊆ V

v4 v1 v3 v5 v7 v0 v2 v6 v8

Winning condition: Inf(ρ) ⊆ C Solution complexity: P Algorithm: dualize + iterated attractor Memory requirements for Player 0: uniform positional Memory requirements for Player 1: uniform positional Dual game: B¨ uchi

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 7/35

slide-8
SLIDE 8

Parity

Name: Parity Game Format: (A, Parity(Ω)) with Ω: V → N

v4/0 v1/3 v3/1 v5/1 v7/3 v0/4 v2/2 v6/2 v8/0

Winning condition: min(Inf(Ω(ρ))) even Solution complexity: NP ∩ co-NP Algorithm: progress measures and many others Memory requirements for Player 0: uniform positional Memory requirements for Player 1: uniform positional Dual game: parity

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 8/35

slide-9
SLIDE 9

Muller

Name: Muller Game Format: (A, Muller(F)) with F ⊆ 2V

v1 v2 v′

1

v′

2

{v1, v2, v′

1, v′ 2}

{v1, v2, v′

1}

{v1, v2, v′

2}

{v1, v′

1}

{v1, v′

2}

{v1} {v1}

Winning condition: Inf(ρ) ∈ F Solution complexity: P, NP ∩ co-NP, PSPACE-complete Algorithm: reduction to parity and many others Memory requirements for Player 0: |V |! Memory requirements for Player 1: |V |! Dual game: Muller

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 9/35

slide-10
SLIDE 10

Generalized Reachability

Name: Generalized Reachability Game Format: (A, GenReach(R)) with R ⊆ 2V Winning condition: ∀R ∈ R. Occ(ρ) ∩ R = ∅ Solution complexity: PSPACE-complete Algorithm: Simulate for |V | · |R| steps Memory requirements for Player 0: 2|R| Memory requirements for Player 1:

  • |R|

⌊|R|/2⌋

  • Dual game:

disjunctive safety

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 10/35

slide-11
SLIDE 11

Weak Parity

Name: Weak Parity Game Format: (A, wParity(Ω)) with Ω: V → N

v4/0 v1/3 v3/1 v5/1 v7/3 v0/4 v2/2 v6/2 v8/0

Winning condition: min(Occ(Ω(ρ))) even Solution complexity: P Algorithm: iterated attractor Memory requirements for Player 0: uniform positional Memory requirements for Player 1: uniform positional Dual game: weak parity

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 11/35

slide-12
SLIDE 12

Weak Muller

Name: Weak Muller Game Format: (A, wMuller(F)) with F ⊆ 2V

s1 h1 u1 d1 s2 h2 u2 d2 s3 ... sn hn un dn c0 d c1 vA vB

Winning condition: Occ(ρ) ∈ F Solution complexity: PSPACE-complete Algorithm: reduction to weak parity or direct one Memory requirements for Player 0: 2|V | Memory requirements for Player 1: 2|V | Dual game: weak Muller

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 12/35

slide-13
SLIDE 13

Request-Response

Name: Request-Response Game Format: (A, ReqRes((Qj, Pj)j∈[k])) with Qj, Pj ⊆ V

vh vi c1 s1 q1 c2 s2 q2 c3 s3 q3 c4 s4 q4 Q1, Q2, Q3, Q4 P1 P2, P3, P4 P2 P3, P4 Q1 P3 P4 Q1, Q2 P4 Q1, Q2, Q3

Winning condition: ∀j ∀n(ρn ∈ Qj → ∃m ≥ n. ρm ∈ Pj) Solution complexity: EXPTIME-complete Algorithm: reduction to B¨ uchi Memory requirements for Player 0: k · 2k Memory requirements for Player 1: 2k Dual game: n/a

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 13/35

slide-14
SLIDE 14

Rabin

Name: Rabin Game Format: (A, Rabin((Qj, Pj)j∈[k])) with Qj, Pj ⊆ V

vh vi c1 s1 q1 c2 s2 q2 c3 s3 q3 c4 s4 q4 Q1, Q2, Q3, Q4 P1 P2, P3, P4 P2 P3, P4 Q1 P3 P4 Q1, Q2 P4 Q1, Q2, Q3

Winning condition: ∃j(Inf(ρ) ∩ Qj = ∅ and Inf(ρ) ∩ Pj = ∅) Solution complexity: NP-complete Algorithm: reduction to parity or direct one Memory requirements for Player 0: uniform positional Memory requirements for Player 1: k! Dual game: Streett

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 14/35

slide-15
SLIDE 15

Streett

Name: Streett Game Format: (A, Streett((Qj, Pj)j∈[k])) with Qj, Pj ⊆ V

vh vi c1 s1 q1 c2 s2 q2 c3 s3 q3 c4 s4 q4 Q1, Q2, Q3, Q4 P1 P2, P3, P4 P2 P3, P4 Q1 P3 P4 Q1, Q2 P4 Q1, Q2, Q3

Winning condition: ∀j(Inf(ρ) ∩ Qj = ∅ ⇒ Inf(ρ) ∩ Pj = ∅) Solution complexity: co-NP-complete Algorithm: reduction to parity or direct one Memory requirements for Player 0: k! Memory requirements for Player 1: uniform positional Dual game: Rabin

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 15/35

slide-16
SLIDE 16

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-17
SLIDE 17

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R)

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-18
SLIDE 18

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S)

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-19
SLIDE 19

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F)

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-20
SLIDE 20

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C)

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-21
SLIDE 21

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω)

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-22
SLIDE 22

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω) Muller(F)

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-23
SLIDE 23

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω) Muller(F) GenReach(R)

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-24
SLIDE 24

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω) Muller(F) GenReach(R) wParity(Ω)

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-25
SLIDE 25

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω) Muller(F) GenReach(R) wParity(Ω) wMuller(F)

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-26
SLIDE 26

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω) Muller(F) GenReach(R) wParity(Ω) wMuller(F) ReqRes(Qj , Pj )

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-27
SLIDE 27

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω) Muller(F) GenReach(R) wParity(Ω) wMuller(F) ReqRes(Qj , Pj ) Rabin(Qj , Pj )

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-28
SLIDE 28

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω) Muller(F) GenReach(R) wParity(Ω) wMuller(F) ReqRes(Qj , Pj ) Rabin(Qj , Pj ) Streett(Qj , Pj )

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-29
SLIDE 29

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω) Muller(F) GenReach(R) wParity(Ω) wMuller(F) ReqRes(Qj , Pj ) Rabin(Qj , Pj ) Streett(Qj , Pj )

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-30
SLIDE 30

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω) Muller(F) GenReach(R) wParity(Ω) wMuller(F) ReqRes(Qj , Pj ) Rabin(Qj , Pj ) Streett(Qj , Pj )

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-31
SLIDE 31

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω) Muller(F) GenReach(R) wParity(Ω) wMuller(F) ReqRes(Qj , Pj ) Rabin(Qj , Pj ) Streett(Qj , Pj )

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-32
SLIDE 32

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω) Muller(F) GenReach(R) wParity(Ω) wMuller(F) ReqRes(Qj , Pj ) Rabin(Qj , Pj ) Streett(Qj , Pj )

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-33
SLIDE 33

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω) Muller(F) GenReach(R) wParity(Ω) wMuller(F) ReqRes(Qj , Pj ) Rabin(Qj , Pj ) Streett(Qj , Pj )

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-34
SLIDE 34

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω) Muller(F) GenReach(R) wParity(Ω) wMuller(F) ReqRes(Qj , Pj ) Rabin(Qj , Pj ) Streett(Qj , Pj )

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-35
SLIDE 35

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω) Muller(F) GenReach(R) wParity(Ω) wMuller(F) ReqRes(Qj , Pj ) Rabin(Qj , Pj ) Streett(Qj , Pj )

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-36
SLIDE 36

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω) Muller(F) GenReach(R) wParity(Ω) wMuller(F) ReqRes(Qj , Pj ) Rabin(Qj , Pj ) Streett(Qj , Pj )

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-37
SLIDE 37

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω) Muller(F) GenReach(R) wParity(Ω) wMuller(F) ReqRes(Qj , Pj ) Rabin(Qj , Pj ) Streett(Qj , Pj )

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-38
SLIDE 38

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω) Muller(F) GenReach(R) wParity(Ω) wMuller(F) ReqRes(Qj , Pj ) Rabin(Qj , Pj ) Streett(Qj , Pj )

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-39
SLIDE 39

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω) Muller(F) GenReach(R) wParity(Ω) wMuller(F) ReqRes(Qj , Pj ) Rabin(Qj , Pj ) Streett(Qj , Pj )

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-40
SLIDE 40

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω) Muller(F) GenReach(R) wParity(Ω) wMuller(F) ReqRes(Qj , Pj ) Rabin(Qj , Pj ) Streett(Qj , Pj )

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-41
SLIDE 41

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω) Muller(F) GenReach(R) wParity(Ω) wMuller(F) ReqRes(Qj , Pj ) Rabin(Qj , Pj ) Streett(Qj , Pj )

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-42
SLIDE 42

Reducibility

Σ1

  • Σ2
  • Σ3
  • Π1
  • Π2
  • Π3

Reach(R) Safety(S) B¨ uchi(F) coB¨ uchi(C) Parity(Ω) Muller(F) GenReach(R) wParity(Ω) wMuller(F) ReqRes(Qj , Pj ) Rabin(Qj , Pj ) Streett(Qj , Pj )

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 16/35

slide-43
SLIDE 43

Wadge Games

(Wadge) reductions are (Wadge) games! A winning strategy for II in the Wadge game W (L, L′) is a witness for the existence of a Wadge reduction L ≤ L′. A winning strategy for I in the Wadge game W (L, L′) is a witness for the non-existence of a Wadge reduction L ≤ L′.

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 17/35

slide-44
SLIDE 44

S2S and Parity Tree Automata

S2S: Monadic second-order logic over two successors PTA: Parity tree automata Both formalisms are equivalent: For every A exists ϕA s.t. t ∈ L(A ) ⇔ t | = ϕA For every ϕ exists Aϕ s.t. t | = ϕ ⇔ t ∈ L(Aϕ) Consequence: Satisfiability of S2S reduces to PTA emptiness (Parity) games everywhere: Acceptance game G(A , t) for complement closure of PTA Emptiness game G(A ) for emptiness check of PTA “The mother of all decidability results”

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 18/35

slide-45
SLIDE 45

Change Log Lecture Notes

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 19/35

slide-46
SLIDE 46

Change Log Lecture Notes 1/2

Old definition: New definition:

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 20/35

slide-47
SLIDE 47

Change Log Lecture Notes 2/2

Graphical notation for finite-state strategies: We represent the initialization function as labeled initial arrows.

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 21/35

slide-48
SLIDE 48

Exam

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 22/35

slide-49
SLIDE 49

Organizational Matters

End-of-term exam When: August 1st, 2016, 10:15 - 12:15 Where: HS 003, Building E1 3 Mode: Open-book What to bring: Student ID Exam inspection: TBA

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 23/35

slide-50
SLIDE 50

Organizational Matters

End-of-term exam When: August 1st, 2016, 10:15 - 12:15 Where: HS 003, Building E1 3 Mode: Open-book What to bring: Student ID Exam inspection: TBA End-of-semester exam: September 20th, 2016 (more information after first exam)

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 23/35

slide-51
SLIDE 51

Questions

Challenge us before we challenge you in the exam.

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 24/35

slide-52
SLIDE 52

Outlook

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 25/35

slide-53
SLIDE 53

(Simple) Stochastic Games

Enter a new player ( ), it flips a coin to pick a successor.

0 wins 1 wins

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 26/35

slide-54
SLIDE 54

(Simple) Stochastic Games

Enter a new player ( ), it flips a coin to pick a successor.

0 wins 1 wins

No (sure) winning strategy... ...but one with probability 1.

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 26/35

slide-55
SLIDE 55

(Simple) Stochastic Games

Enter a new player ( ), it flips a coin to pick a successor.

0 wins 1 wins

No (sure) winning strategy... ...but one with probability 1. Value of the game for Player 0: max

σ

min

τ

pσ,τ where pσ,τ is the probability that Player 0 wins when using strategy σ and Player 1 uses strategy τ.

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 26/35

slide-56
SLIDE 56

Concurrent Games

Both players choose their moves simultaneously Matching pennies:

(heads, heads) (tails, tails) (heads, tails) (tails, heads) (*,*)

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 27/35

slide-57
SLIDE 57

Concurrent Games

Both players choose their moves simultaneously Matching pennies: randomized strategy winning with probability 1.

(heads, heads) (tails, tails) (heads, tails) (tails, heads) (*,*)

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 27/35

slide-58
SLIDE 58

Concurrent Games

Both players choose their moves simultaneously Matching pennies: randomized strategy winning with probability 1.

(heads, heads) (tails, tails) (heads, tails) (tails, heads) (*,*)

The “Snowball Game”:

(run, wait) (hide, throw) (hide, wait) (run, throw) (*,*) (*,*)

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 27/35

slide-59
SLIDE 59

Concurrent Games

Both players choose their moves simultaneously Matching pennies: randomized strategy winning with probability 1.

(heads, heads) (tails, tails) (heads, tails) (tails, heads) (*,*)

The “Snowball Game”: for every ε, randomized strategy winning with probability 1 − ε.

(run, wait) (hide, throw) (hide, wait) (run, throw) (*,*) (*,*)

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 27/35

slide-60
SLIDE 60

Games of Imperfect Information

Players do not observe sequence of states, but sequence of non-unique observations (yellow , purple , blue , brown ). Player 0 picks action a/b, Player 1 resolves non-determinism.

v0 v1 v2 v3 v4 v5 a,b a,b a b b a a,b a,b a,b

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 28/35

slide-61
SLIDE 61

Games of Imperfect Information

Players do not observe sequence of states, but sequence of non-unique observations (yellow , purple , blue , brown ). Player 0 picks action a/b, Player 1 resolves non-determinism.

v0 v1 v2 v3 v4 v5 a,b a,b a b b a a,b a,b a,b

No winning strategy for Player 0: every fixed choice of actions to pick at ( )∗( ) can be countered by going to v1 or v2.

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 28/35

slide-62
SLIDE 62

Pushdown Games

v0/0 v ′

0/1

v1/0 v ′

1/1

v2/0 v ′

2/1

v3/0 v ′

3/1

v4/0 v ′

4/1

v5/0 v ′

5/1

A⊥ AA⊥ AAA⊥ AAAA⊥ AAAAA⊥

v ′′

0 /0

⊥ ... ... qI q1 q2

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 29/35

slide-63
SLIDE 63

Pushdown Games

v0/0 v ′

0/1

v1/0 v ′

1/1

v2/0 v ′

2/1

v3/0 v ′

3/1

v4/0 v ′

4/1

v5/0 v ′

5/1

A⊥ AA⊥ AAA⊥ AAAA⊥ AAAAA⊥

v ′′

0 /0

⊥ ... ... qI q1 q2

Pushdown Parity Games can be reduced to parity games in exponentially sized arenas ⇒ Exptime-complete. Both players have positional winning strategies (but these are now infinite objects!). Finite representation of winning strategies: pushdown automata with output.

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 29/35

slide-64
SLIDE 64

Playing Infinite Games in a Hurry

Parity games in finite time: play until first loop is closed, minimal color in loop determines winner. Positional determinacy ⇒ winning regions preserved

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 30/35

slide-65
SLIDE 65

Playing Infinite Games in a Hurry

Parity games in finite time: play until first loop is closed, minimal color in loop determines winner. Positional determinacy ⇒ winning regions preserved No longer works for Muller games. Need scoring functions:

w 1 1 1 2 Sc{0} Acc{0} Sc{0,1,2} Acc{0,1,2}

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 30/35

slide-66
SLIDE 66

Playing Infinite Games in a Hurry

Parity games in finite time: play until first loop is closed, minimal color in loop determines winner. Positional determinacy ⇒ winning regions preserved No longer works for Muller games. Need scoring functions:

w 1 1 1 2 Sc{0} 1 Acc{0} ∅ Sc{0,1,2} Acc{0,1,2}

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 30/35

slide-67
SLIDE 67

Playing Infinite Games in a Hurry

Parity games in finite time: play until first loop is closed, minimal color in loop determines winner. Positional determinacy ⇒ winning regions preserved No longer works for Muller games. Need scoring functions:

w 1 1 1 2 Sc{0} 1 2 Acc{0} ∅ ∅ Sc{0,1,2} Acc{0,1,2}

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 30/35

slide-68
SLIDE 68

Playing Infinite Games in a Hurry

Parity games in finite time: play until first loop is closed, minimal color in loop determines winner. Positional determinacy ⇒ winning regions preserved No longer works for Muller games. Need scoring functions:

w 1 1 1 2 Sc{0} 1 2 Acc{0} ∅ ∅ ∅ Sc{0,1,2} Acc{0,1,2}

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 30/35

slide-69
SLIDE 69

Playing Infinite Games in a Hurry

Parity games in finite time: play until first loop is closed, minimal color in loop determines winner. Positional determinacy ⇒ winning regions preserved No longer works for Muller games. Need scoring functions:

w 1 1 1 2 Sc{0} 1 2 Acc{0} ∅ ∅ ∅ ∅ Sc{0,1,2} Acc{0,1,2}

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 30/35

slide-70
SLIDE 70

Playing Infinite Games in a Hurry

Parity games in finite time: play until first loop is closed, minimal color in loop determines winner. Positional determinacy ⇒ winning regions preserved No longer works for Muller games. Need scoring functions:

w 1 1 1 2 Sc{0} 1 2 1 Acc{0} ∅ ∅ ∅ ∅ ∅ Sc{0,1,2} Acc{0,1,2}

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 30/35

slide-71
SLIDE 71

Playing Infinite Games in a Hurry

Parity games in finite time: play until first loop is closed, minimal color in loop determines winner. Positional determinacy ⇒ winning regions preserved No longer works for Muller games. Need scoring functions:

w 1 1 1 2 Sc{0} 1 2 1 2 Acc{0} ∅ ∅ ∅ ∅ ∅ ∅ Sc{0,1,2} Acc{0,1,2}

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 30/35

slide-72
SLIDE 72

Playing Infinite Games in a Hurry

Parity games in finite time: play until first loop is closed, minimal color in loop determines winner. Positional determinacy ⇒ winning regions preserved No longer works for Muller games. Need scoring functions:

w 1 1 1 2 Sc{0} 1 2 1 2 Acc{0} ∅ ∅ ∅ ∅ ∅ ∅ ∅ Sc{0,1,2} Acc{0,1,2}

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 30/35

slide-73
SLIDE 73

Playing Infinite Games in a Hurry

Parity games in finite time: play until first loop is closed, minimal color in loop determines winner. Positional determinacy ⇒ winning regions preserved No longer works for Muller games. Need scoring functions:

w 1 1 1 2 Sc{0} 1 2 1 2 Acc{0} ∅ ∅ ∅ ∅ ∅ ∅ ∅ ∅ Sc{0,1,2} Acc{0,1,2}

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 30/35

slide-74
SLIDE 74

Playing Infinite Games in a Hurry

Parity games in finite time: play until first loop is closed, minimal color in loop determines winner. Positional determinacy ⇒ winning regions preserved No longer works for Muller games. Need scoring functions:

w 1 1 1 2 Sc{0} 1 2 1 2 Acc{0} ∅ ∅ ∅ ∅ ∅ ∅ ∅ ∅ Sc{0,1,2} Acc{0,1,2} {0}

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 30/35

slide-75
SLIDE 75

Playing Infinite Games in a Hurry

Parity games in finite time: play until first loop is closed, minimal color in loop determines winner. Positional determinacy ⇒ winning regions preserved No longer works for Muller games. Need scoring functions:

w 1 1 1 2 Sc{0} 1 2 1 2 Acc{0} ∅ ∅ ∅ ∅ ∅ ∅ ∅ ∅ Sc{0,1,2} Acc{0,1,2} {0} {0}

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 30/35

slide-76
SLIDE 76

Playing Infinite Games in a Hurry

Parity games in finite time: play until first loop is closed, minimal color in loop determines winner. Positional determinacy ⇒ winning regions preserved No longer works for Muller games. Need scoring functions:

w 1 1 1 2 Sc{0} 1 2 1 2 Acc{0} ∅ ∅ ∅ ∅ ∅ ∅ ∅ ∅ Sc{0,1,2} Acc{0,1,2} {0} {0} {0, 1}

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 30/35

slide-77
SLIDE 77

Playing Infinite Games in a Hurry

Parity games in finite time: play until first loop is closed, minimal color in loop determines winner. Positional determinacy ⇒ winning regions preserved No longer works for Muller games. Need scoring functions:

w 1 1 1 2 Sc{0} 1 2 1 2 Acc{0} ∅ ∅ ∅ ∅ ∅ ∅ ∅ ∅ Sc{0,1,2} Acc{0,1,2} {0} {0} {0, 1} {0, 1}

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 30/35

slide-78
SLIDE 78

Playing Infinite Games in a Hurry

Parity games in finite time: play until first loop is closed, minimal color in loop determines winner. Positional determinacy ⇒ winning regions preserved No longer works for Muller games. Need scoring functions:

w 1 1 1 2 Sc{0} 1 2 1 2 Acc{0} ∅ ∅ ∅ ∅ ∅ ∅ ∅ ∅ Sc{0,1,2} Acc{0,1,2} {0} {0} {0, 1} {0, 1} {0, 1}

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 30/35

slide-79
SLIDE 79

Playing Infinite Games in a Hurry

Parity games in finite time: play until first loop is closed, minimal color in loop determines winner. Positional determinacy ⇒ winning regions preserved No longer works for Muller games. Need scoring functions:

w 1 1 1 2 Sc{0} 1 2 1 2 Acc{0} ∅ ∅ ∅ ∅ ∅ ∅ ∅ ∅ Sc{0,1,2} Acc{0,1,2} {0} {0} {0, 1} {0, 1} {0, 1} {0, 1}

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 30/35

slide-80
SLIDE 80

Playing Infinite Games in a Hurry

Parity games in finite time: play until first loop is closed, minimal color in loop determines winner. Positional determinacy ⇒ winning regions preserved No longer works for Muller games. Need scoring functions:

w 1 1 1 2 Sc{0} 1 2 1 2 Acc{0} ∅ ∅ ∅ ∅ ∅ ∅ ∅ ∅ Sc{0,1,2} Acc{0,1,2} {0} {0} {0, 1} {0, 1} {0, 1} {0, 1} {0, 1}

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 30/35

slide-81
SLIDE 81

Playing Infinite Games in a Hurry

Parity games in finite time: play until first loop is closed, minimal color in loop determines winner. Positional determinacy ⇒ winning regions preserved No longer works for Muller games. Need scoring functions:

w 1 1 1 2 Sc{0} 1 2 1 2 Acc{0} ∅ ∅ ∅ ∅ ∅ ∅ ∅ ∅ Sc{0,1,2} 1 Acc{0,1,2} {0} {0} {0, 1} {0, 1} {0, 1} {0, 1} {0, 1} ∅

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 30/35

slide-82
SLIDE 82

Playing Infinite Games in a Hurry

Parity games in finite time: play until first loop is closed, minimal color in loop determines winner. Positional determinacy ⇒ winning regions preserved No longer works for Muller games. Need scoring functions:

w 1 1 1 2 Sc{0} 1 2 1 2 Acc{0} ∅ ∅ ∅ ∅ ∅ ∅ ∅ ∅ Sc{0,1,2} 1 Acc{0,1,2} {0} {0} {0, 1} {0, 1} {0, 1} {0, 1} {0, 1} ∅

Theorem

Player i has strategy to bound the opponent’s scores by two when starting in Wi(G).

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 30/35

slide-83
SLIDE 83

Playing Infinite Games in a Hurry

Parity games in finite time: play until first loop is closed, minimal color in loop determines winner. Positional determinacy ⇒ winning regions preserved No longer works for Muller games. Need scoring functions:

w 1 1 1 2 Sc{0} 1 2 1 2 Acc{0} ∅ ∅ ∅ ∅ ∅ ∅ ∅ ∅ Sc{0,1,2} 1 Acc{0,1,2} {0} {0} {0, 1} {0, 1} {0, 1} {0, 1} {0, 1} ∅

Theorem

Player i has strategy to bound the opponent’s scores by two when starting in Wi(G). Corollary: Stopping play after first score reaches value three preserves winning regions (at most exponential play length)

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 30/35

slide-84
SLIDE 84

Games with Costs

Parity game: Player 0 wins from everywhere, but it takes arbitrarily long to “answer” 1 with 0.

1 2

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 31/35

slide-85
SLIDE 85

Games with Costs

Parity game: Player 0 wins from everywhere, but it takes arbitrarily long to “answer” 1 with 0.

1 2 1

Add edge-costs: Player 0 wins if there is a bound b and a position n such that every odd color after n is followed by a smaller even color with cost ≤ b in between ⇒ Player 1 wins example from everywhere (stay longer and longer in 2).

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 31/35

slide-86
SLIDE 86

Games with Costs

Parity game: Player 0 wins from everywhere, but it takes arbitrarily long to “answer” 1 with 0.

1 2 1

Add edge-costs: Player 0 wins if there is a bound b and a position n such that every odd color after n is followed by a smaller even color with cost ≤ b in between ⇒ Player 1 wins example from everywhere (stay longer and longer in 2).

Theorem

Parity games with costs are determined, Player 0 has positional winning strategies, and they can be solved in NP ∩ co-NP.

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 31/35

slide-87
SLIDE 87

Tradeoffs

Every edge has cost 1

3 1 3 1 2 2

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 32/35

slide-88
SLIDE 88

Tradeoffs

Every edge has cost 1

3 1 3 1 2 2

Player 0 has: Positional winning strategy with bound 9. Finite-state strategy of size 2 with bound 8.

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 32/35

slide-89
SLIDE 89

Tradeoffs

Every edge has cost 1

3 1 3 1 2 2

Player 0 has: Positional winning strategy with bound 9. Finite-state strategy of size 2 with bound 8. With d odd colors and d gadgets for each player: Player 0 has: Positional winning strategy with bound d2 + 3d − 1. Finite-state strategy of size 2d − 2 with bound d2 + 2d.

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 32/35

slide-90
SLIDE 90

Many other variants

More winning conditions: various quantitative conditions

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 33/35

slide-91
SLIDE 91

Many other variants

More winning conditions: various quantitative conditions Games on timed automata ⇒ uncountable arenas

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 33/35

slide-92
SLIDE 92

Many other variants

More winning conditions: various quantitative conditions Games on timed automata ⇒ uncountable arenas Play even longer: games of ordinal length

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 33/35

slide-93
SLIDE 93

Many other variants

More winning conditions: various quantitative conditions Games on timed automata ⇒ uncountable arenas Play even longer: games of ordinal length Games with delay: Player 0 is allowed to skip some moves to

  • btain lookahead on Player 1’s moves. Basic question: what

kind of lookahead is necessary to win.

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 33/35

slide-94
SLIDE 94

Many other variants

More winning conditions: various quantitative conditions Games on timed automata ⇒ uncountable arenas Play even longer: games of ordinal length Games with delay: Player 0 is allowed to skip some moves to

  • btain lookahead on Player 1’s moves. Basic question: what

kind of lookahead is necessary to win. More than two players ⇒ no longer zero-sum games. Requires whole new theory (equilibria).

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 33/35

slide-95
SLIDE 95

Many other variants

More winning conditions: various quantitative conditions Games on timed automata ⇒ uncountable arenas Play even longer: games of ordinal length Games with delay: Player 0 is allowed to skip some moves to

  • btain lookahead on Player 1’s moves. Basic question: what

kind of lookahead is necessary to win. More than two players ⇒ no longer zero-sum games. Requires whole new theory (equilibria). And: any combination of extensions discussed above.

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 33/35

slide-96
SLIDE 96

Thesis Topics

DFG project TriCS: Tradeoffs in Controller Synthesis. How to compute optimal strategies?

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 34/35

slide-97
SLIDE 97

Thesis Topics

DFG project TriCS: Tradeoffs in Controller Synthesis. How to compute optimal strategies? Games with delay: how much lookahead is necessary for different winning conditions? Tradeoffs between lookahead and memory? Temporal logics for the specification of reactive systems. ...

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 34/35

slide-98
SLIDE 98

Thesis Topics

DFG project TriCS: Tradeoffs in Controller Synthesis. How to compute optimal strategies? Games with delay: how much lookahead is necessary for different winning conditions? Tradeoffs between lookahead and memory? Temporal logics for the specification of reactive systems. ... Your own idea?

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 34/35

slide-99
SLIDE 99

Thesis Topics

DFG project TriCS: Tradeoffs in Controller Synthesis. How to compute optimal strategies? Games with delay: how much lookahead is necessary for different winning conditions? Tradeoffs between lookahead and memory? Temporal logics for the specification of reactive systems. ... Your own idea? Or what about some open problems: Generalized reachability games with sets of size two: P, NP, or PSPACE? Exact complexity of parity games.

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 34/35

slide-100
SLIDE 100

Thesis Topics

DFG project TriCS: Tradeoffs in Controller Synthesis. How to compute optimal strategies? Games with delay: how much lookahead is necessary for different winning conditions? Tradeoffs between lookahead and memory? Temporal logics for the specification of reactive systems. ... Your own idea? Or what about some open problems: Generalized reachability games with sets of size two: P, NP, or PSPACE? Exact complexity of parity games.

If you are interested in working on current research topics, contact us!

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 34/35

slide-101
SLIDE 101

Thank You & Good luck for the exam

Martin Zimmermann Saarland University Infinite Games - Recap and Outlook 35/35