clarified tensor vs grid differences

overview-burgers-forw.ipynb

@@ -95,7 +95,7 @@
    "source": [
     "\n",
     "Next, we initialize a 1D `velocity` grid from the `INITIAL` numpy array that was converted into a tensor.\n",
-    "The extent of our domain $\\Omega$ is specifiied via the `bounds` parameter $[-1,1]$, and the grid uses periodic boundary conditions (`extrapolation.PERIODIC`). These two properties are the main difference between a tensor and a grid: the latter has boundary conditions and a physical extent.\n",
+    "The extent of our domain $\\Omega$ is specifiied via the `bounds` parameter $[-1,1]$, and the grid uses periodic boundary conditions (`extrapolation.PERIODIC`). These two properties are the main difference between phiflow's tensor and grid objects: the latter has boundary conditions and a physical extent.\n",
     "\n",
     "Just to illustrate, we'll also print some info about the velocity object: it's a `phi.math` tensor with a size of 128. Note that the actual grid content is contained in the `values` of the grid. Below we're printing five entries by using the `numpy()` function to convert the content of the phiflow tensor into a numpy array. For tensors with more dimensions, we'd need to specify the additional dimenions here, e.g., `'y,x,vector'` for a 2D velocity field. (For tensors with a single dimensions we could leave it out.)"
    ]

references.bib

@@ -1033,4 +1033,17 @@
 }
 
 
+@article{lipman2022flow,
+  title={Flow matching for generative modeling},
+  author={Lipman, Yaron and Chen, Ricky TQ and Ben-Hamu, Heli and Nickel, Maximilian and Le, Matt},
+  journal={arXiv:2210.02747}, year={2022} 
+}
+
+@article{liu2022rect,
+  title={Flow straight and fast: Learning to generate and transfer data with rectified flow},
+  author={Liu, Xingchao and Gong, Chengyue and Liu, Qiang},
+  journal={arXiv:2209.03003}, year={2022} 
+}
+
+