Solve(prob, dippyOpts)) function stuck if prob.relaxation = {}

[wangqiuoe]

If I add nothing to prob.relaxation, i.e., simply a MILP problem without decomposition, the Solve() will stuck at some stage, except i add

for i in var:
    prob.relaxation[0] += var[i] >= 0, i

(add no useful constraints)

The whole script is like below, where the function generate_coefficient is from milp_func.py

n_var=2
n_constr=3
args = parseArgs()
args.algo = 'PriceCut'
args.numBlocks = 1
args.numVarsPerBlock = n_var
args.numConsPerBlock = n_constr
args.numLinkingCons = 0
args.randomSeed = 2
args.density = 1

OBJ, MAT, RHS, var = generate_coefficient(args)

prob = DipProblem("MILP", display_mode='matplotlib', display_interval=None)

# add objective
prob += -lpSum([OBJ[i]*var[i] for i in var]), "Objective"

# add constraints
n_cons = len(RHS)
for k in range(n_cons):
    j = "C1_%s" %(k)
    prob += lpSum([MAT[i, j]*var[i] for i in var]) <= RHS[j], j

#for i in var:                                                  # uncomment this two lines, then the code will not stuck 
#    prob.relaxation[0] += var[i] >= 0, i

tol = pow(pow(2, -24), old_div(2.0, 3.0))
dippyOpts = addDippyOpts(args)
dippyOpts['TolZero'] = str(tol)

Solve(prob, dippyOpts)