**Financial support through the following projects:**

UID/MAT/00297/2019

UID/MAT/00297/2013

PEst-OE/MAT/UI0297/2014

PEst-OE/MAT/UI0297/2011

Seminário conjunto de Análise/Álgebra e Lógica

Orador: Charles Johnson (Dept. of Mathematics, College of William and Mary, USA)

Dia e hora: 21/02/2017, terça feira, às 14h

Local: Sala 1.5, ed. VII, FCT-UNL

If $A$ and $B$ are $n$-by-$n$ complex matrices, then $B$ is congruent to $A$ if there is an invertible $n$-by-$n$ matrix $C$, such that $B = C^*AC$. This is an important equivalence relation on matrices that often arises, but it does not preserve eigenvalues. We discuss results that constrain what relation there is between the spectrum of $B$ and that of $A$. This is partly joint work with Susana Furtado (Porto).