Quantization table - initialization and update

[asif-hanif]

Hi @RjDuan
Thank you for excellent work. I have a question regarding initialization and update of Q-table.

(1) In paper, you have mentioned that Q-table is initialized with value of 1 and values are gradually increased during optimization (reference line: after Eq-1 in the paper).

However, in the code Q-table is being initialized with a user-provided value e.g. 40

AdvDrop/infod_sample.py

Line 52 in 35ceeb0

q_ini_table.fill(q_size)

(2) Eq-7 in the paper states that q is updated as follows: $\quad q^{'} = q + \text{sign}(\nabla_{q} \mathcal{L}(x^{'},y))\quad \text{s.t.}\quad||q^{'}-q_{\text{init}}||_{\infty} < \epsilon$

Could you explain if Eq-7 corresponds correctly to the relevant part of the code:

AdvDrop/infod_sample.py

Lines 108 to 110 in 35ceeb0

	for k in self.q_tables.keys():
	self.q_tables[k] = self.q_tables[k].detach() - torch.sign(self.q_tables[k].grad)
	self.q_tables[k] = torch.clamp(self.q_tables[k], self.factor_range[0], self.factor_range[1]).detach()

I have noted following perceived inconsistencies:
a) Negative sign is being used in the update of q-table in code, while Eq-7 uses + sign.
b) Eq-7 with $\ell_{\infty}$ norm suggests that maximum allowable difference in q-table is $\epsilon$ or $\mathrm{q_size}$ i.e. $\mathrm{max}(q^{'}-\mathrm{q_size}) \le \epsilon$, however, code part just keeps each entry of updated q-table in the range of [5, q_size] i.e. $\quad 5 \le q^{'} \le \mathrm{q_size}$

Could you help me clear the above mentioned confusions. Thank you!