// herman's self stabilising algorithm [Her90]
// gxn/dxp 13/07/02

// the procotol is synchronous with no non-determinism (a DTMC)
probabilistic

// module for process 1
module process1

	// bits in the ring (initially all the same i.e. a token in every place)
	x1 : [0..1];
	
	[step] (x1=x5) -> 0.5 : (x1'=0) + 0.5 : (x1'=1);
	[step] !x1=x5 -> (x1'=x5);
	
endmodule

// add further processes through renaming
module process2 = process1[x1=x2, x5=x1 ] endmodule
module process3 = process1[x1=x3, x5=x2 ] endmodule
module process4 = process1[x1=x4, x5=x3 ] endmodule
module process5 = process1[x1=x5, x5=x4 ] endmodule

// cost - 1 in each state (expected steps)
rewards
	
	true : 1;
	
endrewards

// initial states (at least one token i.e. all states)
init
	
	true
	
endinit