Interpolation: LRA interpolation algorithms can be changed with the following option in the command line:

(set-option :interpolation-lra-algorithm <N>) where N can be:

• 0 for Farkas interpolation TACAS’04
• 2 for dual Farkas interpolation
• 4 for decomposed interpolants TACAS’19
• 5 for dual decomposed interpolants TACAS 2019
• 3 for no-man’s land algorithm HVC’17

For the flexible no-man’s land algorithm we can alter the interpolant within the interval alpha = [0 , 1)
To do so, the following option can be used: (set-option :interpolation-lra-factor "alpha")

An example for demonstration purpose:

(set-logic QF_LRA)
(set-option :produce-interpolants true)
(set-option :interpolation-lra-algorithm 3) ;to specify interpolation Alg
(set-option :interpolation-lra-factor "1/5") ;to specify alpha
(declare-fun x () Real)
(declare-fun y () Real)
(declare-fun z () Real)

(assert (!(<= 1 (+ (* 2 x) y (* 3 z) ) ) :named A)) ;to specify partition A
(assert (!(<= 3  (+ (* (- 1) x) (* (- 1) y) (* (- 1) z))) :named B)) ;to specify partition B
(assert (!(<= 0 (+ x (* 3 y) (* (- 1) z) ) ) :named C))
(check-sat)
(get-interpolants A (and B C)) 

To get a model for a SAT formula we use get-value () and specify the desired terms. For e.g,
(get-value (x y)) will print the value for x and y.