Example of Weighted Voting System Undersea target detection system
Weighted Voting System - system output (0,1,x) - voting units outputs (0,1,x) d 1 (I) d 2 (I) d 3 (I) d 4 (I) d 5 (I) d 6 (I) I D(I)D(I) w 1 w 2 w 3 w 4 w 5 w 6 unit 1unit 2 unit 3unit 4 unit 5unit 6 - threshold - system input (0,1) - weights
Decision Making Rule Total weight of units voting for the proposition acceptance Total weight of units voting for the proposition rejection System output
Decision Making Rule if (1- )W n 1 - W n 0 <0 Wn0Wn0 W n 1 Accept Reject if W n 1 =W n 0 =0 otherwise
WVS as a Multi-state System Voting unit j: 3 states: 4 failure modes: d j (0)=1; d j (1)=0; d j (0)=x; d j (1)=x. (1- )W n 1 - W n 0 Entire WVS: Multiple states characterized by different scores 3 possible outputs: 4 failure modes: D(0)=1; D(1)=0; D(0)=x; D(1)=x. Input I
Asymmetric Weighted Voting System - system output (0,1,x) - voting units outputs (0,1,x) - acceptance weights d 1 (I) d 2 (I) d 3 (I) d 4 (I) d 5 (I) d 6 (I) w 1 1 w 1 2 w 1 3 w 1 4 w 1 5 w 1 6 I D(I)D(I) w 0 1 w 0 2 w 0 3 w 0 4 w 0 5 w 0 6 unit 1unit 2 unit 3unit 4 unit 5unit 6 - threshold - system input (0,1) - rejection weights
Decision Making Rule Total weight of units voting for the proposition acceptance Total weight of units voting for the proposition rejection System output
Types of Errors d j (0)=1 (unit fails stuck-at-1) too optimistic q 01 (j) d j (1)=0 (unit fails stuck-at-0) too pessimistic q 10 (j) d j (I)=x (unit fails stuck-at-x) too indecisive q 1x (j), q 0x (j) Voting unit parameters Decision making time t j Rejection weight w j 0 Acceptance weight w j 1 System threshold System Parameters adjustable
Universal generating function technique Score distribution for m voters Score distribution for a single voter Composition operator
)w 01,w 11,…,w 0n,w 1n, ) = arg{R(w 01,w 11,…,w 0n,w 1n, ) max} System Success Probability Optimal adjustment problem Optimization problems
w 1 w 4 w 5 w 2 w 6 w 3 1 2 3 22 11 00 Optimal grouping R(w, , ) max
VU 1VU 2VU 3VU 4VU 5VU 6 w 1 w 2 w 3 w 4 w 5 w 6 P d 1 (P) d 2 (P) d 3 (P) d 4 (P) d 5 (P) d 6 (P) D(P) PG 3PG2PG1 v Optimal distribution among protected groups
Group vulnerability M-number of groups
Order of voting decisions Total weight of units with t j t m voting for the proposition acceptance Total weight of units with t j t m voting for the proposition rejection t1t1 t2t2 tmtm tntn … …
Wm0Wm0 W m 0 Reject V 1 m+1 Wm0Wm0 Accept V 0 m+1 W m 0 Accelerated Decision Making
Q ij m probability of making the decision D(i)=j at the time t m p 0, p 1 - input distribution System reliability and expected decision time
)w 01,w 11,…,w 0n,w 1n, ) = arg{R(w 01,w 11,…,w 0n,w 1n, ) max} subject to T (w 01,w 11,…,w 0n,w 1n, ) T* R T Voting system optimization problem R max T min Two-objective problem: Constrained problem: R max | T<T*
Numerical Example q1xq1x q 10 q0xq0x q 01 tjtj No of unit p 0 =0.3p 0 =0.5p 0 = Q Q Q Q R T Parameters of voting units Parameters of optimal system for T*=35 Reliability vs. expected decision time
References 1. Weighted voting systems: reliability versus rapidity, G. Levitin, Reliability Engineering & System Safety, 89(2) pp (2005). 2. Maximizing survivability of vulnerable weighted voting systems, G. Levitin, Reliability Engineering & System Safety, vol. 83, pp.17-26, (2003). 3. Threshold optimization for weighted voting classifiers, G. Levitin, Naval Research Logistics, vol. 50 (4), pp , (2003). 4. Asymmetric weighted voting systems, G. Levitin, Reliability Engineering & System Safety, vol. 76, pp , (2002). 5. Evaluating correct classification probability for weighted voting classifiers with plurality voting, G. Levitin, European Journal of Operational Research, vol. 141, pp , (2002). 6. Analysis and optimization of weighted voting systems consisting of voting units with limited availability, G. Levitin, Reliability Engineering & System Safety, vol. 73, pp , (2001). 7. Optimal unit grouping in weighted voting systems, G. Levitin, Reliability Engineering & System Safety vol. 72, pp , (2001). 8. Reliability optimization for weighted voting system, G. Levitin, A. Lisnianski, Reliability Engineering & System Safety, vol. 71, pp , (2001).