I am reading Fulton and Harris representation theory.
In the section 8.2 - Examples of Lie Algebras, while calculating the Lie algebra of $SL_n(\mathbb R),$ the author tell that by definition $$ A_t(e_1) \wedge\cdots \wedge A_t(e_n) \equiv e_1 \wedge \cdots \wedge e_n$$ for any basis $\{e_i\} $ of $\mathbb R ^n$ where $\{ A_t\}$ is an arc in $SL_n(\mathbb R)$ with $A_0 = I$ and $A_0' = X$
Can someone tell me exactly what defintion to the author is referring, I have looked appendix where exterior product is defined and earlier chapters, I am not able to find out in the book.