The survivor's guilt
Why should this narrator struggle so obsessively with survivor's guilt? He doesn't share in the guilt of the Holocaust? His community is torn apart by the events, and he is merely witnessing these events, but in the aftermath, he can't help but to feel like there was something he should have done. The irony of the guilt is that it isn't his to bear, but in a way, it does indicate the communal culpability of the West for tolerating hatred and anti-semitism—although this specific person was too young to have played a serious part in that.
Math class
Before the Holocaust, math class made sense. The narrator goes to class, he does his homework, he takes his tests, and typically he gets good grades. That all changes in the wake of the Holocaust. In light of that, the math class seems hysterically irrelevant. Why on earth would he stop thinking about the Holocaust for long enough to study and do his homework? The trauma and tragedy is so overwhelming that it consumes him; math class becomes an ironic symbol for meaninglessness.
Numbers and names
There is an ironic synchronicity between the numbers of the narrator's math class and the numbers of the Holocaust victims. The numbers in concentration camps are a bitter reminder of the dehumanizing effect of the Holocaust and Nazi anti-semitism. Then again, the numbers of death tolls can be equally dehumanizing. How does one conceive "six million?" For the narrator though, the deaths are close to home, literally. He doesn't see the Holocaust through numbers; he sees the Holocaust through real names, people he loved and misses in their absence.
The dual rejection
Although the closest thing to romance in the novel is the relationship between the narrator and Micol, the story doesn't feature their union. Instead, it puts the narrator in the confusing emotional space of rejection. Instead of losing the love of his life, he loses the very chance of attaining love. The dual rejection is a common motif in literature; when Micol invites the narrator into her garden, he denies her, and when he later confesses his adoration, she confesses that she doesn't really have those feelings. The issue is of timing; they need timing in order to become a couple, and this points to the finality of death, because their time together ends before it can begin.
The ironic prologue
The chronology of the book is ironic, because it front-loads the impact of the Holocaust and then rewinds to show the state of innocence that was lost. This use of in medias res is a painful tool that makes the novel melancholic and nostalgic. To the narrator, he wants to escape backward in time, but he can't. Likewise, the ironic reversal of time in the novel shows that we are not revisiting innocence; we are merely witnessing the mournful attempts to recapture the paradise that has been lost.
