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183 lines
10 KiB
183 lines
10 KiB
// CROWDS [Reiter,Rubin]
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// Vitaly Shmatikov, 2002
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// Note:
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// Change everything marked CWDSIZ when changing the size of the crowd
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// Change everything marked CWDMAX when increasing max size of the crowd
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dtmc
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// Probability of forwarding
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const double PF = 0.8;
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// Probability that a crowd member is bad
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const double badC = 0.091;
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// const double badC = 0.167;
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const int TotalRuns=3; // Total number of protocol runs to analyze
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const int CrowdSize=4; // CWDSIZ: actual number of good crowd members
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const int MaxGood=20; // CWDMAX: maximum number of good crowd members
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// Process definitions
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module crowds
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// Auxiliary variables
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launch: bool init true; // Start modeling?
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new: bool init false; // Initialize a new protocol instance?
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runCount: [0..TotalRuns] init TotalRuns; // Counts protocol instances
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start: bool init false; // Start the protocol?
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run: bool init false; // Run the protocol?
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lastSeen: [0..MaxGood] init MaxGood; // Last crowd member to touch msg
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good: bool init false; // Crowd member is good?
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bad: bool init false; // ... bad?
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recordLast: bool init false; // Record last seen crowd member?
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badObserve: bool init false; // Bad members observes who sent msg?
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deliver: bool init false; // Deliver message to destination?
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done: bool init false; // Protocol instance finished?
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// Counters for attackers' observations
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// CWDMAX: 1 counter per each good crowd member
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observe0: [0..TotalRuns] init 0;
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observe1: [0..TotalRuns] init 0;
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observe2: [0..TotalRuns] init 0;
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observe3: [0..TotalRuns] init 0;
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observe4: [0..TotalRuns] init 0;
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observe5: [0..TotalRuns] init 0;
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observe6: [0..TotalRuns] init 0;
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observe7: [0..TotalRuns] init 0;
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observe8: [0..TotalRuns] init 0;
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observe9: [0..TotalRuns] init 0;
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observe10: [0..TotalRuns] init 0;
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observe11: [0..TotalRuns] init 0;
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observe12: [0..TotalRuns] init 0;
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observe13: [0..TotalRuns] init 0;
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observe14: [0..TotalRuns] init 0;
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observe15: [0..TotalRuns] init 0;
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observe16: [0..TotalRuns] init 0;
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observe17: [0..TotalRuns] init 0;
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observe18: [0..TotalRuns] init 0;
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observe19: [0..TotalRuns] init 0;
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[] launch -> (new'=true) & (runCount'=TotalRuns) & (launch'=false);
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// Set up a new protocol instance
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[] new & runCount>0 -> (runCount'=runCount-1) & (new'=false) & (start'=true);
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// SENDER
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// Start the protocol
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[] start -> (lastSeen'=0) & (run'=true) & (deliver'=false) & (start'=false);
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// CROWD MEMBERS
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// Good or bad crowd member?
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[] !good & !bad & !deliver & run ->
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1-badC : (good'=true) & (recordLast'=true) & (run'=false) +
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badC : (bad'=true) & (badObserve'=true) & (run'=false);
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// GOOD MEMBERS
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// Forward with probability PF, else deliver
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[] good & !deliver & run -> PF : (good'=false) + 1-PF : (deliver'=true);
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// Record the last crowd member who touched the msg;
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// all good members may appear with equal probability
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// Note: This is backward. In the real protocol, each honest
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// forwarder randomly chooses the next forwarder.
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// Here, the identity of an honest forwarder is randomly
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// chosen *after* it has forwarded the message.
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[] recordLast & CrowdSize=2 ->
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1/2 : (lastSeen'=0) & (recordLast'=false) & (run'=true) +
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1/2 : (lastSeen'=1) & (recordLast'=false) & (run'=true);
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[] recordLast & CrowdSize=4 ->
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1/4 : (lastSeen'=0) & (recordLast'=false) & (run'=true) +
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1/4 : (lastSeen'=1) & (recordLast'=false) & (run'=true) +
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1/4 : (lastSeen'=2) & (recordLast'=false) & (run'=true) +
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1/4 : (lastSeen'=3) & (recordLast'=false) & (run'=true);
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[] recordLast & CrowdSize=5 ->
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1/5 : (lastSeen'=0) & (recordLast'=false) & (run'=true) +
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1/5 : (lastSeen'=1) & (recordLast'=false) & (run'=true) +
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1/5 : (lastSeen'=2) & (recordLast'=false) & (run'=true) +
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1/5 : (lastSeen'=3) & (recordLast'=false) & (run'=true) +
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1/5 : (lastSeen'=4) & (recordLast'=false) & (run'=true);
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[] recordLast & CrowdSize=10 ->
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1/10 : (lastSeen'=0) & (recordLast'=false) & (run'=true) +
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1/10 : (lastSeen'=1) & (recordLast'=false) & (run'=true) +
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1/10 : (lastSeen'=2) & (recordLast'=false) & (run'=true) +
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1/10 : (lastSeen'=3) & (recordLast'=false) & (run'=true) +
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1/10 : (lastSeen'=4) & (recordLast'=false) & (run'=true) +
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1/10 : (lastSeen'=5) & (recordLast'=false) & (run'=true) +
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1/10 : (lastSeen'=6) & (recordLast'=false) & (run'=true) +
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1/10 : (lastSeen'=7) & (recordLast'=false) & (run'=true) +
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1/10 : (lastSeen'=8) & (recordLast'=false) & (run'=true) +
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1/10 : (lastSeen'=9) & (recordLast'=false) & (run'=true);
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[] recordLast & CrowdSize=15 ->
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1/15 : (lastSeen'=0) & (recordLast'=false) & (run'=true) +
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1/15 : (lastSeen'=1) & (recordLast'=false) & (run'=true) +
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1/15 : (lastSeen'=2) & (recordLast'=false) & (run'=true) +
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1/15 : (lastSeen'=3) & (recordLast'=false) & (run'=true) +
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1/15 : (lastSeen'=4) & (recordLast'=false) & (run'=true) +
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1/15 : (lastSeen'=5) & (recordLast'=false) & (run'=true) +
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1/15 : (lastSeen'=6) & (recordLast'=false) & (run'=true) +
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1/15 : (lastSeen'=7) & (recordLast'=false) & (run'=true) +
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1/15 : (lastSeen'=8) & (recordLast'=false) & (run'=true) +
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1/15 : (lastSeen'=9) & (recordLast'=false) & (run'=true) +
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1/15 : (lastSeen'=10) & (recordLast'=false) & (run'=true) +
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1/15 : (lastSeen'=11) & (recordLast'=false) & (run'=true) +
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1/15 : (lastSeen'=12) & (recordLast'=false) & (run'=true) +
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1/15 : (lastSeen'=13) & (recordLast'=false) & (run'=true) +
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1/15 : (lastSeen'=14) & (recordLast'=false) & (run'=true);
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[] recordLast & CrowdSize=20 ->
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1/20 : (lastSeen'=0) & (recordLast'=false) & (run'=true) +
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1/20 : (lastSeen'=1) & (recordLast'=false) & (run'=true) +
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1/20 : (lastSeen'=2) & (recordLast'=false) & (run'=true) +
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1/20 : (lastSeen'=3) & (recordLast'=false) & (run'=true) +
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1/20 : (lastSeen'=4) & (recordLast'=false) & (run'=true) +
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1/20 : (lastSeen'=5) & (recordLast'=false) & (run'=true) +
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1/20 : (lastSeen'=6) & (recordLast'=false) & (run'=true) +
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1/20 : (lastSeen'=7) & (recordLast'=false) & (run'=true) +
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1/20 : (lastSeen'=8) & (recordLast'=false) & (run'=true) +
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1/20 : (lastSeen'=9) & (recordLast'=false) & (run'=true) +
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1/20 : (lastSeen'=10) & (recordLast'=false) & (run'=true) +
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1/20 : (lastSeen'=11) & (recordLast'=false) & (run'=true) +
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1/20 : (lastSeen'=12) & (recordLast'=false) & (run'=true) +
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1/20 : (lastSeen'=13) & (recordLast'=false) & (run'=true) +
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1/20 : (lastSeen'=14) & (recordLast'=false) & (run'=true) +
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1/20 : (lastSeen'=15) & (recordLast'=false) & (run'=true) +
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1/20 : (lastSeen'=16) & (recordLast'=false) & (run'=true) +
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1/20 : (lastSeen'=17) & (recordLast'=false) & (run'=true) +
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1/20 : (lastSeen'=18) & (recordLast'=false) & (run'=true) +
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1/20 : (lastSeen'=19) & (recordLast'=false) & (run'=true);
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// BAD MEMBERS
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// Remember from whom the message was received and deliver
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// CWDMAX: 1 rule per each good crowd member
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[] lastSeen=0 & badObserve & observe0 <TotalRuns -> (observe0' =observe0 +1) & (deliver'=true) & (run'=true) & (badObserve'=false);
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[] lastSeen=1 & badObserve & observe1 <TotalRuns -> (observe1' =observe1 +1) & (deliver'=true) & (run'=true) & (badObserve'=false);
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[] lastSeen=2 & badObserve & observe2 <TotalRuns -> (observe2' =observe2 +1) & (deliver'=true) & (run'=true) & (badObserve'=false);
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[] lastSeen=3 & badObserve & observe3 <TotalRuns -> (observe3' =observe3 +1) & (deliver'=true) & (run'=true) & (badObserve'=false);
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[] lastSeen=4 & badObserve & observe4 <TotalRuns -> (observe4' =observe4 +1) & (deliver'=true) & (run'=true) & (badObserve'=false);
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[] lastSeen=5 & badObserve & observe5 <TotalRuns -> (observe5' =observe5 +1) & (deliver'=true) & (run'=true) & (badObserve'=false);
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[] lastSeen=6 & badObserve & observe6 <TotalRuns -> (observe6' =observe6 +1) & (deliver'=true) & (run'=true) & (badObserve'=false);
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[] lastSeen=7 & badObserve & observe7 <TotalRuns -> (observe7' =observe7 +1) & (deliver'=true) & (run'=true) & (badObserve'=false);
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[] lastSeen=8 & badObserve & observe8 <TotalRuns -> (observe8' =observe8 +1) & (deliver'=true) & (run'=true) & (badObserve'=false);
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[] lastSeen=9 & badObserve & observe9 <TotalRuns -> (observe9' =observe9 +1) & (deliver'=true) & (run'=true) & (badObserve'=false);
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[] lastSeen=10 & badObserve & observe10<TotalRuns -> (observe10'=observe10+1) & (deliver'=true) & (run'=true) & (badObserve'=false);
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[] lastSeen=11 & badObserve & observe11<TotalRuns -> (observe11'=observe11+1) & (deliver'=true) & (run'=true) & (badObserve'=false);
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[] lastSeen=12 & badObserve & observe12<TotalRuns -> (observe12'=observe12+1) & (deliver'=true) & (run'=true) & (badObserve'=false);
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[] lastSeen=13 & badObserve & observe13<TotalRuns -> (observe13'=observe13+1) & (deliver'=true) & (run'=true) & (badObserve'=false);
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[] lastSeen=14 & badObserve & observe14<TotalRuns -> (observe14'=observe14+1) & (deliver'=true) & (run'=true) & (badObserve'=false);
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[] lastSeen=15 & badObserve & observe15<TotalRuns -> (observe15'=observe15+1) & (deliver'=true) & (run'=true) & (badObserve'=false);
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[] lastSeen=16 & badObserve & observe16<TotalRuns -> (observe16'=observe16+1) & (deliver'=true) & (run'=true) & (badObserve'=false);
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[] lastSeen=17 & badObserve & observe17<TotalRuns -> (observe17'=observe17+1) & (deliver'=true) & (run'=true) & (badObserve'=false);
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[] lastSeen=18 & badObserve & observe18<TotalRuns -> (observe18'=observe18+1) & (deliver'=true) & (run'=true) & (badObserve'=false);
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[] lastSeen=19 & badObserve & observe19<TotalRuns -> (observe19'=observe19+1) & (deliver'=true) & (run'=true) & (badObserve'=false);
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// RECIPIENT
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// Delivery to destination
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[] deliver & run -> (done'=true) & (deliver'=false) & (run'=false) & (good'=false) & (bad'=false);
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// Start a new instance
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[] done -> (new'=true) & (done'=false) & (run'=false) & (lastSeen'=MaxGood);
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endmodule
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label "observeIGreater1" = observe1>1|observe2>1|observe3>1;
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label "observeOnlyTrueSender" = observe0>1 & observe1<=1 & observe2<=1 & observe3<=1;
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