ICG Chapter 1 Introduction

Questions about the lecture 'Infinte computations and games' of the RWTH Aachen Chapter 1 Introduction

Questions about the lecture 'Infinte computations and games' of the RWTH Aachen Chapter 1 Introduction


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What is the characteristic?

[sofar.motivation]

Theory of regular languages and finite automata on finite words // FoSAP

What is the characteristic?

[now.motivation, 3]

1. Theory of regular languages and finite automata on (one-sided) infinite words

2. Automata on infinite trees

3. Games of infinite duration

List the reasons!

[why.now.motivation, 3]

1. Model executions of non-terminating systems

2. Represent real numbers with infinite words

3. Decision procedure for logics on infinite structures

List them!

[executions.why.now.motivation, 3]

1. One execution is a infinite word

2. All executions are a infinite tree

3. Interaction with environment is a infinite game

What happened 1960?

[history]

Decision problems in logic and circuit design

What happened 1962?

[history]

Program synthesis and Church’s problem

What are the characteristics?

[1962.history, 2]

1. Running program generates a non-terminating sequence of output beta from input alpha signals

2. Task is to automatically synthesize a program from the specification phi(alpha,beta)

What happened 1969?

[history]

View Church’s problem as game between player input and player output

What happened 1980s?

[history]

Theoretical foundations for applications in verification

What happened 1990s?

[history]

Industrial applications in verification // Tool “Spin”

What happened 2000s?

[history]

First tools for synthesis

List them!

[notations, 7+2]

1. Sigma is a finite alphabet

2. a,b,c,… represent letters of an alphabet

3. Sigma* is the set of finite words over Sigma

4. u,v,w,… represent finite words

5. eps is the empty word

6. Sigma+ is the set of non-empty finite words over Sigma

7. N is the set of natural numbers including 0

 

8. Infinite words

9. Languages

What are the characteristics?

[infwords.notations, 3]

1. Infinite sequences over a Sigma

2. By help of omega // ababab… = (ab)omega

3. Can formally be defined as functions alpha: N→Sigma

What are the characteristics?

[languages.notations, 3]

1. All words with a certain property over Sigma

2. omega defines order type of natural numbers // Two sided infinite words are also possible

3. L is called Büchi recognizable if there is an NBA A with L(A)=L

What are the characteristics?

[büchi, 3]

1. Always NBA if not mentioned explicitly

2. Every DBA can be viewed as NBA

3. There are Büchi recognizable languages that are no DBA recognizable

What is the definition?

[DBA.büchi, 4]

1. A=(Q,Sigma,q0,delta,F) with delta: Q x Simga → Q

2. Unique run on alpha in Sigmaomega is rho in Qomega

3. A accepts alpha if rho(i) in F for infinitely many I

4. L(A):={alpha in Sigmaomega| A accepts alpha} the omega-language

What is the definition?

[rho.DBA.büchi, 2]

1. rho(0)=q0

2. rho(i+1)=delta(rho(i),alpha(i))

What is the definition?

[NBA.büchi, 4]

1. A=(Q,Sigma,q0,Delta,F) with Delta \subseteq Q x Simga x Q

2. Run on alpha in Sigmaomega is rho in Qomega

3. A accepts alpha is there is at least one accepting run of A on alpha

4. Language is defined as for DBA

What is the definition?

[rho.NBA.büchi, 2]

1. rho(0)=q0

2. (rho(i),alpha(i),rho(i+1)) in Delta

What is the definition?

[theorem.büchi]

The class of DBA recognizable languages is not closed under complement