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As far as I see you look for something like:

var('x,y,z,w,a,b,c,d') 
V2=[x,y,z,w,a,b,c,d]
s=[V2[i]==V2[7-i] for i in [0..3]]
solve(s,x,y,z,w,a,b,c,d)

Here one obtains that

[[x == r1, y == r2, z == r3, w == r4, a ==r4, b == r3, c == r2, d == r1]]