vault backup: 2023-05-27 23:02:51

Affected files:
.obsidian/graph.json
.obsidian/workspace.json
STEM/AI/Neural Networks/Activation Functions.md
STEM/AI/Neural Networks/CNN/CNN.md
STEM/AI/Neural Networks/CNN/FCN/FCN.md
STEM/AI/Neural Networks/CNN/FCN/FlowNet.md
STEM/AI/Neural Networks/CNN/FCN/Highway Networks.md
STEM/AI/Neural Networks/CNN/FCN/ResNet.md
STEM/AI/Neural Networks/CNN/FCN/Skip Connections.md
STEM/AI/Neural Networks/CNN/GAN/DC-GAN.md
STEM/AI/Neural Networks/CNN/GAN/GAN.md
STEM/AI/Neural Networks/CNN/UpConv.md
STEM/img/highway-vs-residual.png
STEM/img/imagenet-error.png
STEM/img/resnet-arch.png
STEM/img/resnet-arch2.png
STEM/img/skip-connections 1.png
STEM/img/upconv-matrix-result.png
STEM/img/upconv-matrix-transposed-result.png
STEM/img/upconv-matrix.png
STEM/img/upconv-transposed-matrix.png
STEM/img/upconv.png

AI/Neural Networks/Activation Functions.md

@@ -53,7 +53,7 @@ Rectilinear
 - For deep networks
 - $y=max(0,x)$
 - CNNs
-	- Breaks associativity of successive convolutions
+	- Breaks associativity of successive [[convolution]]s
 		- Critical for learning complex functions
 	- Sometimes small scalar for negative
 		- Leaky ReLu

AI/Neural Networks/CNN/CNN.md

@@ -15,7 +15,7 @@
 
 # Full Connected
 [[MLP|Dense]]
-- Move from convolutional operations towards vector output
+- Move from [[Convolutional Layer|convolutional]] operations towards vector output
 - Stochastic drop-out
 	- Sub-sample channels and only connect some to [[MLP|dense]] layers
 
@@ -28,14 +28,14 @@
 
 # Finetuning
 - Observations
-	- Most CNNs have similar weights in conv1
-	- Most useful CNNs have several conv layers
+	- Most CNNs have similar weights in [[Convolutional Layer|conv1]]
+	- Most useful CNNs have several [[Convolutional Layer|conv layers]]
 		- Many weights
 		- Lots of training data
 	- Training data is hard to get
 		- Labelling
 - Reuse weights from other network
-- Freeze weights in first 3-5 conv layers
+- Freeze weights in first 3-5 [[Convolutional Layer|conv layers]]
 	- Learning rate = 0
 	- Randomly initialise remaining layers
 	- Continue with existing weights

AI/Neural Networks/CNN/FCN/FCN.md

@@ -1,6 +1,6 @@
 Fully [[Convolution]]al Network
 
-Convolutional and up-convolutional layers with [[Activation Functions#ReLu|ReLu]] but no others (pooling)
+[[Convolutional Layer|Convolutional]] and [[UpConv|up-convolutional layers]] with [[Activation Functions#ReLu|ReLu]] but no others (pooling)
 - All some sort of Encoder-Decoder
 
 Contractive → [[UpConv]]

AI/Neural Networks/CNN/FCN/FlowNet.md

@@ -7,7 +7,7 @@ Optical Flow
 
 ![[flownet.png]]
 
-# Skip Connections
+# [[Skip Connections]]
 - Further through the network information is condensed
 	- Less high frequency information
 - Link encoder layers to [[upconv]] layers

AI/Neural Networks/CNN/FCN/Highway Networks.md

@@ -0,0 +1,9 @@
+- [[Skip connections]] across individual layers
+	- Conditionally
+- Soft gates
+	- Learn vs carry
+- Gradients propagate further
+- Inspired by [[LSTM]] [[RNN]]s
+
+![[highway-vs-residual.png]]
+![[skip-connections 1.png]]

AI/Neural Networks/CNN/FCN/ResNet.md

@@ -12,14 +12,18 @@
 
 # Design
 
-- Skips across pairs of conv layers
+- Skips across pairs of [[Convolutional Layer|conv layers]]
 	- Elementwise addition
 - All layer 3x3 kernel
 - Spatial size halves each layer
 - Filters doubles each layer
-- Fully convolutional
+- [[FCN|Fully convolutional]]
 	- No fc layer
-	- No pooling
+	- No [[Max Pooling|pooling]]
 		- Except at end
 	- No dropout
 
+![[imagenet-error.png]]
+
+![[resnet-arch.png]]
+![[resnet-arch2.png]]

AI/Neural Networks/CNN/FCN/Skip Connections.md

@@ -1,16 +1,16 @@
-- Output of conv, c, layers are added to inputs of upconv, d, layers
+- Output of [[Convolutional Layer|conv]], c, layers are added to inputs of [[upconv]], d, layers
 - Element-wise, not channel appending
 - Propagate high frequency information to later layers
 - Two types
 	- Additive
-		- Resnet
-		- Super-resolution auto-encoder
+		- [[ResNet]]
+		- [[Super-resolution]] auto-encoder
 - Concatenative
 	- Densely connected architectures
 	- DenseNet
-	- FlowNet
+	- [[FlowNet]]
 
-![[skip-connections.png]]
+![[STEM/img/skip-connections.png]]
 
 [AI Summer - Skip Connections](https://theaisummer.com/skip-connections/)
-[Arxiv - Visualising the Loss Landscape](https://arxiv.org/abs/1712.09913)aaaaa
+[Arxiv - Visualising the Loss Landscape](https://arxiv.org/abs/1712.09913)

AI/Neural Networks/CNN/GAN/DC-GAN.md

@@ -1,4 +1,4 @@
-Deep Convolutional [[GAN]]
+Deep [[Convolution]]al [[GAN]]
 ![[dc-gan.png]]
 
 - Generator
@@ -13,7 +13,7 @@ Deep Convolutional [[GAN]]
 - Discriminator
 	- Contractive
 	- Cross-entropy [[Deep Learning#Loss Function|loss]]
-	- Conv and leaky [[Activation Functions#ReLu|ReLu]] layers only
+	- [[Convolutional Layer|Conv]] and leaky [[Activation Functions#ReLu|ReLu]] layers only
 	- Normalised output via [[Activation Functions#Sigmoid|sigmoid]]
 
 ## [[Deep Learning#Loss Function|Loss]]

AI/Neural Networks/CNN/GAN/GAN.md

@@ -1,4 +1,4 @@
-# Fully Convolutional
+# Fully [[Convolution]]al
 - Remove [[Max Pooling]]
 	- Use strided [[upconv]]
 - Remove [[MLP|FC]] layers

AI/Neural Networks/CNN/UpConv.md

@@ -0,0 +1,35 @@
+- Fractionally strided convolution
+- Transposed [[convolution]]
+	- Like a deep interpolation
+- Convolution with a fractional input stride
+- Up-sampling is convolution 'in reverse'
+	- Not an actual inverse convolution
+- For scaling up by a factor of $f$
+	- Consider as a [[convolution]] of stride $1/f$
+- Could specify kernel
+	- Or learn
+- Can have multiple upconv layers
+	- Separated by [[Activation Functions#ReLu|ReLu]]
+	- For non-linear up-sampling conv
+	- Interpolation is linear
+
+![[upconv.png]]
+
+# Convolution Matrix
+Normal
+
+![[upconv-matrix.png]]
+
+- Equivalent operation with a flattened input
+	- Row per kernel location
+- Many-to-one operation
+
+![[upconv-matrix-result.png]]
+
+[Understanding transposed convolutions](https://www.machinecurve.com/index.php/2019/09/29/understanding-transposed-convolutions/)
+
+## Transposed
+![[upconv-transposed-matrix.png]]
+- One-to-many
+
+![[upconv-matrix-transposed-result.png]]