def forward(self, input_t: BK.Expr, edges: BK.Expr, mask_t: BK.Expr):
_isize = self.conf._isize
_ntype = self.conf.type_num
_slen = BK.get_shape(edges, -1)
# --
edges3 = edges.clamp(min=-1, max=1) + 1
edgesF = edges + _ntype # offset to positive!
# get hid
hid0 = BK.matmul(input_t, self.W_hid).view(
BK.get_shape(input_t)[:-1] + [3, _isize]) # [*, L, 3, D]
hid1 = hid0.unsqueeze(-4).expand(-1, _slen, -1, -1,
-1) # [*, L, L, 3, D]
hid2 = BK.gather_first_dims(hid1.contiguous(), edges3.unsqueeze(-1),
-2).squeeze(-2) # [*, L, L, D]
hidB = self.b_hid[edgesF] # [*, L, L, D]
_hid = hid2 + hidB
# get gate
gate0 = BK.matmul(input_t, self.W_gate) # [*, L, 3]
gate1 = gate0.unsqueeze(-3).expand(-1, _slen, -1, -1) # [*, L, L, 3]
gate2 = gate1.gather(-1, edges3.unsqueeze(-1)) # [*, L, L, 1]
gateB = self.b_gate[edgesF].unsqueeze(-1) # [*, L, L, 1]
_gate0 = BK.sigmoid(gate2 + gateB)
_gmask0 = (
(edges != 0) |
(BK.eye(_slen) > 0)).float() * mask_t.unsqueeze(-2) # [*,L,L]
_gate = _gate0 * _gmask0.unsqueeze(-1) # [*,L,L,1]
# combine
h0 = BK.relu((_hid * _gate).sum(-2)) # [*, L, D]
h1 = self.drop_node(h0)
# add & norm?
if self.ln is not None:
h1 = self.ln(h1 + input_t)
return h1
def nmarginal_unproj(scores_expr, mask_expr, lengths_arr, labeled=True):
assert labeled
with BK.no_grad_env():
scores_shape = BK.get_shape(scores_expr)
maxlen = scores_shape[1]
# todo(warn): it seems that float32 is not enough for inverse when the model gets better (scores gets more diversed)
diag1_m = BK.eye(maxlen).double() # [m, h]
scores_expr_d = scores_expr.double()
mask_expr_d = mask_expr.double()
invalid_pad_expr_d = 1.-mask_expr_d
# [*, m, h]
full_invalid_d = (diag1_m + invalid_pad_expr_d.unsqueeze(-1) + invalid_pad_expr_d.unsqueeze(-2)).clamp(0., 1.)
full_invalid_d[:, 0] = 1.
#
# first make it unlabeled by sum-exp
scores_unlabeled = BK.logsumexp(scores_expr_d, dim=-1) # [BS, m, h]
# force small values at diag entries and padded ones
scores_unlabeled_diag_neg = scores_unlabeled + Constants.REAL_PRAC_MIN * full_invalid_d
# # minus the MaxElement to make it more stable with larger values, to make it numerically stable.
# [BS, m, h]
# todo(+N): since one and only one Head is selected, thus minus by Max will make it the same?
# I think it will be canceled out since this is like left-mul A by a diag Q
scores_unlabeled_max = (scores_unlabeled_diag_neg.max(-1)[0] * mask_expr_d).unsqueeze(-1) # [BS, m, 1]
scores_exp_unlabeled = BK.exp(scores_unlabeled_diag_neg - scores_unlabeled_max)
# # todo(0): co-work with minus-max, force too small values to be 0 (serve as pruning, the gap is ?*ln(10)).
# scores_exp_unlabeled *= (1 - (scores_exp_unlabeled<1e-10)).double()
# force 0 at diag entries (again)
scores_exp_unlabeled *= (1. - diag1_m)
# assign non-zero values (does not matter) to (0, invalid) to make the matrix inversable
scores_exp_unlabeled[:, :, 0] += (1. - mask_expr_d) # the value does not matter?
# construct L(or K) Matrix: L=D-A
A = scores_exp_unlabeled
A_sum = A.sum(dim=-1, keepdim=True) # [BS, m, 1]
# # =====
# todo(0): can this avoid singular matrix: feels like adding aug-values to h==0(COL0) to-root scores.
# todo(+N): there are cases that the original matrix is not inversable (no solutions for trees)!!
A_sum += 1e-6
# A_sum += A_sum * 1e-4 + 1e-6
#
D = A_sum.expand(scores_shape[:-1])*diag1_m # [BS, m, h]
L = D - A # [BS, m, h]
# get the minor00 matrix
LM00 = L[:, 1:, 1:] # [BS, m-1, h-1]
# # Debug1
# try:
# # for idx in range(scores_shape[0]):
# # one_det = float(LM00[idx].det())
# # assert not math.isnan(one_det)
# # LM00_CPU = LM00.cpu()
# # LM00_CPU_inv = LM00_CPU.inverse()
# scores_exp_unlabeled_CPU = scores_exp_unlabeled.cpu()
# LM00_CPU = LM00.cpu()
# assert BK.has_nan(LM00_CPU) == 0
# except:
# assert False, "Problem here"
#
# det and inverse; using LU decomposition to hit two birds with one stone.
diag1_m00 = BK.eye(maxlen-1).double()
# deprecated operation
# LM00_inv, LM00_lu = diag1_m00.gesv(LM00) # [BS, m-1, h-1]
# # todo(warn): lacking P here, but the partition should always be non-negative!
# LM00_det = BK.abs((LM00_lu*diag1_m00).sum(-1).prod(-1)) # [BS, ]
# d(logZ)/d(LM00) = (LM00^-1)^T
# # directly inverse (need pytorch >= 1.0)
# LM00_inv = LM00.inverse()
LM00_inv = BK.get_inverse(LM00, diag1_m00)
LM00_grad = LM00_inv.transpose(-1, -2) # [BS, m-1, h-1]
# marginal(m,h) = d(logZ)/d(score(m,h)) = d(logZ)/d(LM00) * d(LM00)/d(score(m,h)) = INV_mm - INV_mh
# padding and minus
LM00_grad_pad = BK.pad(LM00_grad, [1,0,1,0], 'constant', 0.) # [BS, m, h]
LM00_grad_pad_sum = (LM00_grad_pad * diag1_m).sum(dim=-1, keepdim=True) # [BS, m, 1]
marginals_unlabeled = A * (LM00_grad_pad_sum - LM00_grad_pad) # [BS, m, h]
# make sure each row sum to 1.
marginals_unlabeled[:, 0, 0] = 1.
# finally, get labeled results
marginals_labeled = marginals_unlabeled.unsqueeze(-1) * BK.exp(scores_expr_d - scores_unlabeled.unsqueeze(-1))
#
# # Debug2
# try:
# # for idx in range(scores_shape[0]):
# # one_det = float(LM00[idx].det())
# # assert not math.isnan(one_det)
# # LM00_CPU = LM00.cpu()
# # LM00_CPU_inv = LM00_CPU.inverse()
# scores_exp_unlabeled_CPU = scores_exp_unlabeled.cpu()
# LM00_CPU = LM00.cpu()
# marginals_unlabeled_CPU = marginals_unlabeled.cpu()
# assert BK.has_nan(marginals_unlabeled_CPU) == 0
# #
# global last_lm00, last_marginals
# last_lm00 = LM00_CPU
# last_marginals = marginals_unlabeled_CPU
# except:
# assert False, "Problem here"
#
# back to plain float32
masked_marginals_labeled = marginals_labeled * (1.-full_invalid_d).unsqueeze(-1)
ret = masked_marginals_labeled.float()
return _ensure_margins_norm(ret)
