In the last chapter, I discussed contests having a single asymmetry which is unambiguously known to both contestants at the start of the contest; the obvious example is the asymmetry between the owner of a resource and an intruder. A number of complexities arise in actual animal contests. The following classification is not exhaustive: it is intended mainly as a guide to Chapters 8–10.

1. 1. A single asymmetry initially present, known certainly to both contestants.

2. (a) Asymmetry uncorrelated with payoff or RHP (‘resource-holding power’.

3. (b) Payoff and/or RHP differ between the two roles.

4. (c) Strategy sets as well as payoffs and RHP differ between the two roles (e.g. male–female and parent–offspring contests).

Types 1(a) and 1(b) were the topic of the last chapter. Type 1(c) is discussed in Chapter 10.

1. 2. A single asymmetry present, but each contestant knows only its own state. This is the ‘game with random rewards’, which was discussed in Chapter 3, and Appendix G.

2. 3. A single asymmetry present, but information about it is uncertain (e.g. differences in size or strength). Such contests involve a phase of ‘assessment’. Considerable theoretical difficulties arise if the information acquired during assessment is uncertain.

3. 4. More than one asymmetry present.

This chapter deals with types 3 and 4. First, I discuss the case in which unambiguous information about the asymmetry can be acquired. This raises no particular difficulties; as expected, an assessed asymmetry can settle contests without escalation. Some illustrative examples are then discussed.