diff --git a/2023/2023-03-16-ProgrammingWithJulia-4/slides/4a-scipkgs.md b/2023/2023-03-16-ProgrammingWithJulia-4/slides/4a-scipkgs.md
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+<div class=leader>
+<i class="twa twa-horse-face"></i>
+<i class="twa twa-zebra"></i>
+<i class="twa twa-chicken"></i>
+<i class="twa twa-unicorn"></i>
+<br>
+Ecosystem
+</div>
+
+
+
+# Cornerstones
+
+- `Symbolics.jl`
+- `ForwardDiff.jl`
+- SciMl
+- `JuMP.jl`
+- `Flux.jl`
+
+
+
+# Symbolics.jl
+
+- declare symbolic variables: `@variables`
+  - tricky question: can this be done without a macro?
+- `substitute`
+- `derivative`
+- `solve_for` (linear eqns)
+- `build_function`
+- `using Latexify` → `latexify`
+
+
+
+# SYSTEMATIC INTERLUDE
+
+What is the difference between:
+- a variable `a`
+- a variable `a` that was marked as a `@variable`
+- a symbol `:a`
+...?
+
+(How does that extend to expressions?)
+
+
+
+# ForwardDiff.jl
+
+Main task:
+- generate better functions than Symbolics
+- avoid the intermediate symbolic phase
+- support arrays
+
+```julia
+f(x) = 4*x[1]^2 - 3*x[2]^3 + 2*x[3]^4 + 32 - 5*x[4] + 2*x[1]*x[2]*x[3] + 2*x[2] + x[2]*x[3]*x[4] + 2*x[1]*x[3]+x[4] + 3*(x' * x)
+```
+
+Task: find the minimum of the function (with gradient descent)
+
+Pro-level: try with Symbolics
+
+
+
+# SciML.jl
+
+If you are into:
+- ODEs
+- ODE solvers
+- Reaction networks
+- dynamic systems
+- N-body simulations
+- nonlinear optimization
+...SciML probably has a package for it.
+
+
+
+# JuMP.jl
+
+JuMP is for constrained optimization (LP, MILP, QP).
+
+- make a `Model` using optimizers (let's use `GLPK.Optimizer`)
+- `@variables`
+- `@constraint`
+- `@objective`
+- `optimize!`
+- `value`
+
+Task:
+- Factory A produces 5 drinks and 1 foods for 1 coal
+- Factory B produces 1 drink and 4 foods for 1 coal
+- People need roughly 10 drinks for 7 foods
+- Each person needs 1 food a day, and you have 100 persons
+- How much coal do you need daily?
+
+
+# Flux.jl
+
+Flux is like the Keras stack, but written in a single language.
+
+Let's have a look at the website.
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diff --git a/2023/2023-03-16-ProgrammingWithJulia-4/slides/index.md b/2023/2023-03-16-ProgrammingWithJulia-4/slides/index.md
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+
+# Programming with Julia
+
+## March 2023
+
+<div style="top: 6em; left: 0%; position: absolute;">
+    <img src="theme/img/lcsb_bg.png">
+</div>
+
+<div style="top: 1em; left: 60%; position: absolute;">
+    <img src="slides/img/julia.svg" height="200px">
+    <h1 style="margin-top:3ex; margin-bottom:3ex;">4: Numeric&scientific ecosystem</h1>
+    <h4>
+        Miroslav Kratochvíl<br>
+        Laurent Heirendt<br>
+        LCSB, DSSE<br>
+    </h4>
+</div>
+
+<link rel="stylesheet" href="https://lcsb-biocore.github.io/icons-mirror/twemoji-amazing.css">
+<style>
+	code {border: 2pt dotted #f80; padding: .4ex; border-radius: .7ex; color:#444; }
+	.reveal pre code {border: 0; font-size: 18pt; line-height:27pt;}
+	em {color: #e02;}
+	li {margin-bottom: 1ex;}
+	div.leader {font-size:400%; line-height:120%; font-weight:bold; margin: 1em;}
+	section {padding-bottom: 10em;}
+</style>
diff --git a/2023/2023-03-16-ProgrammingWithJulia-4/slides/list.json b/2023/2023-03-16-ProgrammingWithJulia-4/slides/list.json
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@@ -0,0 +1,4 @@
+[
+    { "filename": "index.md" },
+    { "filename": "4a-scipkgs.md" }
+]