Integral curve [Arn1, p.17, l.1-l.2]; integral surface [Joh, p.9, l.16].
Variational equation: The key concept is first approximation [Arn1, p.94,
l.9 & l.15].
A formal definition may not reveal its real meaning when there is a
story behind the nomenclature.
The term "autonomous" means "time-independent". A nonautonomous system may
occur because it is only a part of the whole system [Arn1, p.117, l.4-l.21].
The wave equation: Pictures of waves [Sne, p.216, Fig.34; p.218, Fig.36].
The terms "elliptic, hyperbolic, parabolic" for PDE's are adopted from
figures in [Bir, p.125] because the classification of linear systems for
PDE's [Pet, p.59, (3)] is similar to that of linear systems for ODE's.
The Riemann P-function
For the symbolic form given in [Inc1, p.162, l.5], [Inc1,
p.162, l.7] calls it the Riemann P-function, while [Wat1, p.206, l.-10;
Guo, p.69, l.-5] call it the Riemann P-equation. We
should judge for ourselves which terminology is more appropriate rather than blindly
follow the authority. Since the symbolic form is used to represent the solution of a
differential equation, the former terminology is more appropriate.