Minesweeper example

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Minesweeper example

• MAS course
• Ramon F. Brena

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Minesweeper
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Environment perspective
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Minesweeper Environment

• Board will be managed by an agent
• Controller agent
• There will be one agent for each square in the
  grid
• Solver agents

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Organizational Perspective

Controller
Solvers
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Roles

• Controller
• Consults and modifies squares status
• Responds to solver queries, giving information
  about the result of an action
• Solver
• Proposes actions on the grid (stomp, mark)
• Ask neighbor solvers about their status
• Discusses with other solvers

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Controller role

• Permissions
• Read square (i,j) public status in
• Unknown (covered)
• 0 8 (bombs near)
• Read square (I,j) hidden status in
• Free
• Bomb
• Modify public status from Unknown to 0..8

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Controller role

• Responsibilities
• Liveness properties
• (PerformStompMark)? Win Lose
• Safety properties
• Maintain board coherence (e.g. no 2 is near 3
  bombs, etc.)
• Do not accept solutions after Lose

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Solver Role

• No permissions
• Responsibilities
• Liveness
• (ConsultNeighStatus PerformStomp Mark) ?
• Safety
• Do not stomp unless sure or stuck

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PerformStomp Protocol

• Description
• A solver agent decides to stomp, and communicates
  its decision to the controller. The controller
  performs a stomping action and returns the
  resulting status to the solver.
• Initiator A solver
• Respondent The controller

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PerformStomp Protocol

• Inputs (information used by the role initiator
  while enacting the protocol)
• Solvers position / identity
• Outputs (information supplied by the protocol
  responder during interaction)
• Solvers new status

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PerformStomp diagram
Protocol Name PerformStomp
InputSolvers (I,j)
Initiator A Solver
Respondent Controller
OutputSolvers new status
Description A solver agent decides to stomp, and
communicates its decision to the controller. The
controller performs a stomping action and returns
the resulting status to the solver
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ConsultNeighStatus
Protocol Name ConsultNeighStatus
InputSolvers (I,j)
Initiator Solver (i,j)
Respondent Solver (n,m)
OutputSolver (n,m) status
Description A solver agent in position (I,j)
asks agent in position (n,m) about its status,
and a corresponding answer is issued by solver at
(n,m)
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ConsultNeighStatus issues

• Is it possible to ask about a distant solver
  status?
• If NO, how this restriction is enforced?
• Other possibility is to ask the controller, not
  other solvers

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Initialization issues

• How to start the game?
• What solver is going to stomp first?
• At startup, solvers could wait a random amount of
  time, then ask for a reservation to stomp first
  to all other solvers
• When a reservation demand is received, no other
  reservation is demanded, and a warrant is issued

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FirstStomp protocol
Protocol Name FirstStomp
InputSolvers (I,j)
Initiator Solver (i,j)
Respondent Solver (n,m)
OutputWarrant from (n,m)Confirmation from (i,j)
Description A solver agent tries to be the first
to stomp on the grid, so asks other solvers to
refrain from doing so and to give a warrant
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Refinement cycle
Roles' Protocols and Activities
Protocols details
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Other issues

• User interface
• Could be part of Controller
• Could include a step button
• Game termination
• Win-related protocols
• Lose-related protocols
• Harder situations (not locally solvable)