From 76ea597b3e3e249e7b1e3ed22ae53475d96b0c02 Mon Sep 17 00:00:00 2001
From: Steven Morad <smorad@um.edu.mo>
Date: Sat, 22 Nov 2025 02:50:52 +0800
Subject: [PATCH] DeltaNet fixes

---
 memorax/equinox/semigroups/delta.py  |  4 +++-
 memorax/equinox/semigroups/deltap.py |  3 ++-
 memorax/equinox/semigroups/gdn.py    | 11 +++++++++--
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/memorax/equinox/semigroups/delta.py b/memorax/equinox/semigroups/delta.py
index 4e99713..3317a3e 100644
--- a/memorax/equinox/semigroups/delta.py
+++ b/memorax/equinox/semigroups/delta.py
@@ -107,10 +107,11 @@ def forward_map(
     ) -> DeltaFWPRecurrentStateWithReset:
         emb, start = x
         k = phi(self.K(emb))
+        k = k / (jnp.linalg.norm(k) + 1e-6)  # normalize key
         v = self.V(emb)
         beta = psi(self.w(emb))
         M = jnp.eye(self.recurrent_size) - beta * jnp.outer(k, k)
-        X = beta * jnp.outer(v, k)
+        X = beta * jnp.outer(v, k) 
         return (M, X), start
 
     @jaxtyped(typechecker=typechecker)
@@ -123,6 +124,7 @@ def backward_map(
         emb, start = x
         (M, X), reset_flag = h
         q = phi(self.Q(emb))
+        q = q / (jnp.linalg.norm(q) + 1e-6)  # normalize query
         return self.output(X @ q)
 
     @jaxtyped(typechecker=typechecker)
diff --git a/memorax/equinox/semigroups/deltap.py b/memorax/equinox/semigroups/deltap.py
index 36b0305..df2855c 100644
--- a/memorax/equinox/semigroups/deltap.py
+++ b/memorax/equinox/semigroups/deltap.py
@@ -112,7 +112,7 @@ def forward_map(
     ) -> DeltaProductRecurrentStateWithReset:
         emb, start = x
         k = phi(self.K(emb)).reshape(-1, self.rank)
-        k = k / (1e-8 + jnp.linalg.norm(k, axis=0, keepdims=True))
+        k = k / (jnp.linalg.norm(k) + 1e-6)  # normalize key
         v = self.V(emb).reshape(-1, self.rank)
         alpha = jax.nn.sigmoid(self.alpha(emb))
         beta = psi(self.w(emb)).reshape(-1, self.rank)
@@ -134,6 +134,7 @@ def backward_map(
         emb, start = x
         (M, X), reset_flag = h
         q = phi(self.Q(emb))
+        q = q / (jnp.linalg.norm(q) + 1e-6)  # normalize query
         return self.output(X @ q)
 
     @jaxtyped(typechecker=typechecker)
diff --git a/memorax/equinox/semigroups/gdn.py b/memorax/equinox/semigroups/gdn.py
index cc9d18d..263aa28 100644
--- a/memorax/equinox/semigroups/gdn.py
+++ b/memorax/equinox/semigroups/gdn.py
@@ -3,6 +3,7 @@
 import jax
 import jax.numpy as jnp
 from beartype import beartype as typechecker
+import equinox as eqx
 from equinox import nn
 from jaxtyping import Array, Float, PRNGKeyArray, Shaped, jaxtyped
 
@@ -21,7 +22,7 @@
 def phi(x, key=None):
     # https://arxiv.org/pdf/2102.11174 uses relu
     # https://arxiv.org/pdf/2406.06484 uses silu
-    return jax.nn.relu(x)
+    return jax.nn.silu(x)
 
 def psi(x, key=None):
     # https://arxiv.org/pdf/2102.11174 uses sigmoid
@@ -100,7 +101,11 @@ def __init__(self, hidden_size, recurrent_size, key):
         self.Q = nn.Linear(hidden_size, recurrent_size, use_bias=False, key=keys[1])
         self.V = nn.Linear(hidden_size, recurrent_size, use_bias=False, key=keys[2])
         self.w = nn.Linear(hidden_size, 1, key=keys[3])
-        self.alpha = nn.Linear(hidden_size, 1, key=keys[4])
+        alpha = nn.Linear(hidden_size, 1, key=keys[4])
+        # Initialize alpha bias to 4.0 so that sigmoid(alpha) is near 1.0 at init
+        self.alpha = eqx.tree_at(
+            lambda l: l.bias, alpha, jnp.full_like(alpha.bias, 4.0)
+        )
         self.output = nn.Linear(recurrent_size, hidden_size, key=keys[5])
 
     @jaxtyped(typechecker=typechecker)
@@ -109,6 +114,7 @@ def forward_map(
     ) -> GDNRecurrentStateWithReset:
         emb, start = x
         k = phi(self.K(emb))
+        k = k / (jnp.linalg.norm(k) + 1e-6)  # normalize key
         v = self.V(emb)
         beta = psi(self.w(emb))
         alpha = jax.nn.sigmoid(self.alpha(emb))
@@ -126,6 +132,7 @@ def backward_map(
         emb, start = x
         (M, X), reset_flag = h
         q = phi(self.Q(emb))
+        q = q / (jnp.linalg.norm(q) + 1e-6)  # normalize query
         return self.output(X @ q)
 
     @jaxtyped(typechecker=typechecker)