316 Current Trends in Bayesian Methodology with Applications
x = (x
1
, x
2
, x
3
, x
4
, x
5
) will satisfy
c
1
x
1
+ c
2
x
2
+ c
3
x
3
+ c
4
x
4
≤ b,
x
1
, x
2
, x
3
, x
4
≥ 0 ,
x
4
≤ n
4
x
1
, x
2
, x
3
, x
4
integer
x
5
∈ {0, 1},
where n
4
is the maximum number of access doors that may be replaced. We
denote by B the se t of feasible portfolios.
We describe now the impact of countermeasures on the fare evasion pro-
portion. Assume that N, the number of customers in the planning period,
may be modelled as a Poisson pr ocess of rate λ. Let p(x) be the proportion of
standard fraudsters when we implement the security plan x, and q(x
1
) be the
proportion of customers inspected (x
2
, x
3
, x
4
, x
5
do not serve for inspection
purposes). Then, if we assume no extra cost for an annoyed customer, the
operator shall ...