A receiver adapted to mitigating inter-symbol interference in a received signal (508; 508'; 508"), wherein the receiver is for use with a transmitter that outputs a sequence of K symbols using a modulation constellation Q of size q, said receiver comprising: a two-stage equalizer (502; 502'; 502") including: a demodulation first stage (504; 504'; 504") arranged to process the received signal (508; 508'; 508") and produce initial symbol decisions ŝ 1:K (510', 510a"); and a non-linear equalization second stage (506; 506'; 506") arranged to use the received signal (508; 508'; 508") to perform a sequential search in an attempt to improve upon the initial symbol decisions (510', 510a"), wherein if the second stage (506; 506'; 506") is able to improve upon the initial symbol decisions (510', 510a"), then the second stage (506; 506'; 506") is arranged to obtain an output sequence (512; 512'; 512") from the sequential search, and if the second stage (506; 506'; 506") is not able to improve upon the initial symbol decisions (510', 510a"), then the second stage (506; 506'; 506") is arranged to output the initial symbol decisions as the output sequence (512; 512'; 512"), and the first stage (504") is arranged to output the initial symbol decisions ŝ 1:K and reliability measures μ k (510b"), where the reliability measures μ k (510b") indicate a reliability of each symbol ŝ k at index k, characterized in that the second stage (506") is arranged to use the initial symbol decisions ŝ 1:K and the reliability measures μ k (510b") to restrict a fanout of at least one index k of the sequential search by setting a restricted constellation Q ' k of size q ' k, where the value of q' k is between 1 and q, wherein, if μ k is higher, then size q' k of restricted constellation Q ' k is smaller, and, if μ k is lower, then size q' k of restricted constellation Q ' k is larger. a demodulation first stage (504; 504'; 504") arranged to process the received signal (508; 508'; 508") and produce initial symbol decisions ŝ 1:K (510', 510a"); and a non-linear equalization second stage (506; 506'; 506") arranged to use the received signal (508; 508'; 508") to perform a sequential search in an attempt to improve upon the initial symbol decisions (510', 510a"), wherein if the second stage (506; 506'; 506") is able to improve upon the initial symbol decisions (510', 510a"), then the second stage (506; 506'; 506") is arranged to obtain an output sequence (512; 512'; 512") from the sequential search, and if the second stage (506; 506'; 506") is not able to improve upon the initial symbol decisions (510', 510a"), then the second stage (506; 506'; 506") is arranged to output the initial symbol decisions as the output sequence (512; 512'; 512"), and the first stage (504") is arranged to output the initial symbol decisions ŝ 1:K and reliability measures μ k (510b"), where the reliability measures μ k (510b") indicate a reliability of each symbol ŝ k at index k, characterized in that the second stage (506") is arranged to use the initial symbol decisions ŝ 1:K and the reliability measures μ k (510b") to restrict a fanout of at least one index k of the sequential search by setting a restricted constellation Q ' k of size q ' k, where the value of q' k is between 1 and q, wherein, if μ k is higher, then size q' k of restricted constellation Q ' k is smaller, and, if μ k is lower, then size q' k of restricted constellation Q ' k is larger.